You Are in Command Now



"O'Brien: It's an old naval tradition. Whoever's in command of a ship, regardless of rank, is referred to as "captain." Nog: You mean if I had to take command, I would be called "captain," too? O'Brien: Cadet, by the time you took command, there'd be nobody left to call you anything."

- Star Trek: Deep Space Nine, "Behind the Lines"

A character, working in the military, is suddenly forced into duties that by all rights ought to belong to someone of much higher rank; everyone who ought to be doing those duties has unexpectedly found themselves dead, indisposed, or unavailable.

This is most likely to occur in the navy or its Space Operatic equivalent—it requires that the plot be isolated enough from the rest of the military that they can't just respond by immediately sending a replacement of the appropriate rank. Trapped Behind Enemy Lines is another possibility, as is the characters becoming prisoners of war, where under The Laws and Customs of War, the senior-most commands, even if none of them belonged to the same unit prior to capture.

In Real Life, if there are a number of survivors of the same rank, the most senior of them holds command (unless otherwise designated, ie, the XO is always second-in-command and the OPS officer is always third, regardless of rank). In fiction, the situation is often adequately chaotic that the one that actually gives orders may find himself pressed into command and leadership. (In really chaotic situations, it may dawn on him that he is giving orders to superiors—at which point, the highest-ranking superior generally tells everyone to follow their plan. Contrast With Due Respect.)

Often this requires them to press juniors and otherwise unsuitable people into roles as their subordinates. Occasionally, the promotee subsequently becomes Drunk with Power.

If the dead commander was A Father to His Men, the new one may find his troops are Losing the Team Spirit over his death—though he can issue a Rousing Speech reminding them that the dead commander would be So Proud of You if they soldier on.

Usually the "promotion" involved is strictly temporary. Either the people who are supposed to do the job will return from whatever made them unavailable in the first place, or a replacement will eventually appear. On the other hand, in a continuing series, a stint of You Are in Command Now is not exactly a hindrance to promotion, since it shows Leadership.

Compare Unexpected Successor, Falling Into the Cockpit, Take Up My Sword, Time to Step Up Commander.

If the promotion occurs because the promoted deliberately offed the person occupying the spot in the first place, and this is considered a legitimate situation, then you have a case of Klingon Promotion.

Note that if the character does not command, it falls under Field Promotion, since it is handled out by the commander, even if he would not normally be the commander.

Advertising

 * In a 1990s radio campaign for a Vancouver RV dealership called Fraser Way, the owner of a competing dealership needed ideas on how to beat Fraser Way's deals, so every employee became the Sales Manager for a few seconds.

Anime & Manga
"Amy: [Being the commander] is a little dangerous... but... it's not like a major emergency is going to happen anytime soo-- (cue warning klaxons as the Wolkenritter are spotted)"
 * Gundam:
 * This is the premise of the original Mobile Suit Gundam: Bright Noa, a mere officer trainee with no battle experience whatsoever, is forced to become The Captain of the Cool Starship White Base when nearly all of his superior officers are killed in the first episode surprise attack by Zeon Federation, and the one survivor (the captain) succumbing to his wounds shortly afterward. This also nicely mirrors the protagonist Amuro Ray Falling Into the Cockpit of the eponymous battle robot he never seen before.
 * In Mobile Suit Gundam Seed, the same thing happens to Lieutenant Murrue Ramius, who becomes The Captain of the Archangel after all higher-ranking officers are killed in a surprise attack. She offers command to Lieutenant Mu La Flaga, who has seniority (but identical rank) and greater experience, but he insists on deferring to her because he is the only available pilot other than Kira. Since the ship has two functional mecha at the time, both Mu and Kira are needed in the cockpits, leaving Murrue the only choice.
 * Bridge Bunny Amy of Lyrical Nanoha gets smacked with this trope in the second season when the Arthra is being refitted with the Arc-en-ciel, requiring everyone above her to go to the main office a few dimensions over. She just has to tempt fate.


 * Lt. Havoc finds himself in this position towards the end of Fullmetal Alchemist,
 * Done in repeatedly in Legend of the Galactic Heroes.
 * Played straight at the beginning of the series when Yang Wenli is given command of the 2nd Fleet by his severely wounded commanding officer during the height of the Battle of Astarte as he's the highest-ranking officer left who's not incapacitated. He then proceeds to save the fleet from complete destruction.
 * . It is a multiple subversion actually: Officers higher than him are still around, but they just cannot choose whom among them will  (first subversion), so they chooses   to act both as a figurehead (second subversion) and to arbitrate between them when they don't agree with each other, so while he seems to be a powerless puppet, he IS giving orders to people higher than him in the hierarchy and they willingly obey such orders. (But then again,  .)
 * Bleach:
 * In the movie The Diamond Dust Rebellion, Rangiku has to take temporary command of Squad 10 after Captain Hitsugaya turns up missing. She does a damn good job of it, too.
 * In canon, Lieutenants Izuru Kira and Shuuhei Hisagi take command of their squads after . Momo Hinamori would've done the same due to, but she was both physically and emotionally unfit for duty at the time.

Film

 * Corporal Hicks in Aliens becomes able to authorize a nuclear attack thanks to alien-caused attrition in the higher ranks, though the company lieutenant was only wounded, not killed, in an incident precipitated by his own ineptitude. When he's up and around again, he seems to acknowledge his failure of command, allowing Hicks and a civilian Ripley to continue calling the shots. (Granted, the situation had devolved to the point that any attempt to re-assert command had a good chance of being ignored anyway.)
 * Repeatedly happens in the Starship Troopers movie. It's all but stated that the Mobile Infantry work on a system similar to Klingon Promotion, except you don't kill your superior (except to spare them from being captured and having their brains sucked out), the enemy does.
 * Star Wars:
 * Toyed with repeatedly in The Empire Strikes Back (the Trope Namer): Darth Vader, as Supreme Commander, holds no formal rank in the Imperial system save as an agent of the Emperor himself (meaning that any order he gives is treated as no different from an order by the Emperor), allowing him to hand out nice little impromptu promotions by Force-choking the incompetent officers. In one scene, he chokes Admiral Ozzel for screwing up, and immediately addresses Ozzel's XO Captain Piett as Admiral Piett, putting him in command right then and there (before Ozzel's body has even hit the floor). In the Star Wars Expanded Universe, the novel Heir To The Empire reveals that while it was risky, serving aboard Vader's flagship, the Executor, was also seen as the fast track to promotion for the sufficiently quick-thinking and competent—and that Vader's tactics worked, weeding out the officers who couldn't keep up, so that only the very good or the very lucky were left. This meant, though, that when Executor was destroyed at Endor, the Empire lost more than just a powerful warship...
 * In the first movie, when Luke's commander is killed in the assault on the Death Star, this huge, meaningful music cue plays to signify that Luke is now in command of the mission. (What's left of it; just him and his wingmen.)
 * There's another, more subtle instance of this a few minutes earlier. After Darth Vader shoots down two of Gold Squadron's Y-wings during their trench run, the lone survivor—Gold Five—radios Red Leader to report their destruction. Red Leader responds with "I copy, Gold Leader," acknowledging that as the sole surviving member of the squadron he became its leader. At least, until Vader shot him down too a few seconds later.
 * The 2009 Star Trek movie has this happen to every single character. At least five different characters inherit command of at least two different ships during the movie. Russian whiz kid Chekov is the only one of the main characters who ends up in his position without someone else getting sick or flat out killed, and he is briefly given command of the Enterprise when everyone else is away.
 * In U-571, the main character is an American submarine officer whose captain is killed in action. Being second-in-command, he then has to take charge of the crew to complete the mission, evading depth charge attacks, engaging in an underwater battle, and making horrible decisions that cost members of his crew their lives....all while manning a German-built sub whose controls they are utterly unfamiliar with. At one point, a crewman says that the Chief Petty Officer should assume command rather than Lt. Tyler. The Chief shuts him down very quickly.
 * In Zulu, Lieutenant Chard of the Royal Engineers finds himself in command of an obscure supply depot that has lost its major and come under attack by Zulus. Lieutenant Bromhead, despite being an infantryman, must defer to Chard because he received his commission three months later. In reality, Chard had three years' seniority over Bromhead and was explicitly left in command by the Major in charge of the post. Seniority aside, Bromhead was deaf, which was the reason he was posted to Rorke's Drift, where no action was expected.
 * In The Warriors, the gang's leader Cleon is killed in the opening of the film. Second-in-command Swan takes his place, though the bruiser of the group, Ajax, tries to dispute this.
 * The Guns of Navarone. Major Franklin starts off as mission leader thanks to his rank, but Mallory becomes the de facto leader after Franklin is incapacitated by injury.
 * In the opening scenes of Saving Private Ryan (on Omaha Beach), Captain Miller receives more or less this exact response from his sergeant after asking who's in command of their area of the beach. He's already in command of most of the men around him, though, he was merely confirming that nobody higher-up was around.
 * Full Metal Jacket gives us this line: "You're senior NCO, Cowboy. You're in charge. Continue on with the patrol, and call in at the next checkpoint." Cowboy's response to this lies somewhere at the end of the sliding scale of Oh Crap.
 * On several occassions in Downfall, Hitler randomly promotes officers to higher military positions. General Weidling is ordered to defend Berlin when he only came in to attest that he didn't move his command post and therefore shouldn't be executed. Ritter von Greim is an even better example however: he was also already a general, but when he makes it to the bunker he is put in command of the entire German air force (which is all but completely defunct by this point in time), and told that he has to rebuild it from the ground up. When Hitler starts claiming that he'll be able to give Greim a thousand jet aircraft on short notice, it's become obvious that reality and him don't see eye to eye anymore.
 * All of these happened in Real Life - ironically, von Greim's You Are in Command Now moment nearly led to another You Are in Command Now - Hitler could very easily have conferred the promotion by phone or telegram, but he just had to give von Greim the command in person, with the result that von Greim's pitiful little aeroplane was nearly shot down over the Tiergarten and von Greim injured so badly he couldn't fly it. If his lover, top display pilot Hanna Reitsch hadn't been there to fly the plane form the backseat, he would certainly have been killed.
 * In Terminator 3,

Literature
""Who is," Uexkull asked, his voice like a slither of dry scale, "second in command? Say, for instance, if the garrison commander is suddenly deprived of brain activity?""
 * Jules Verne wrote a novel called Dick Sand, A Captain at Fifteen, where all the crew of a ship is killed while hunting a whale, except for the eponymous character. This is Older Than Radio.
 * Elizabeth Moon has a good Space Is an Ocean example, in Winning Colors: Esmay Suiza takes command of a small spaceship, despite being a junior-grade lieutenant who's about twelfth in the chain of command, because everyone ahead of her is either in the pay of the enemy or killed by those who are.
 * Midshipman's Hope by David Feintuch is all about this trope. Deconstructed and subverted as well.
 * Dan Abnett's Warhammer 40,000 Gaunt's Ghosts novels
 * Brutally crushed in Sabbat Martyr. in Ensign Valdemeer, an eager young junior officer on a grand Imperial warship. When most of the bridge crew is slain and the captain cut off from his usual empathic command of the ship, he asks for Valdemeer to take the helm. Valdemeer tries to fight back, but the ship is already near-destroyed, and he and the captain are killed without being able to inflict telling damage on their killers.
 * In Ghostmaker, when a small group of Ghosts were protecting some wounded Volpone blue bloods, Culcis, one of the wounded, got up despite his injuries and got some of his fellows to follow him, and volunteered that they could shoot. When he appears again in Necropolis, he has risen in rank, and tells Corbec that the doctor was kind enough to mention his part in the defense, which had gotten his officers' eyes on him.
 * Necropolis:
 * Milo takes the initiative after a sergeant was killed. Gaunt wrestles with putting him in the position but decides that being the youngster trooper, it would be too much (Rawne considers this a mistake on his part).
 * Later in the battle, Gaunt is temporarily "promoted" to the be supreme commander of all Imperial forces in Vervunhive, despite the fact that he's only a Colonel-Commissar. This is because the other ranking officers are either dead, disgraced, or smart enough to defer to him. However, after the battle, he is restored to his regular rank, though he keeps the city's ceremonial power sword.
 * In Traitor General, Uexkull kills a local commander for not searching vigorously enough to find infiltrators, and then disables his second in command for not answering promptly enough when he asked. The third-in-command is asked about the infiltrators and leaps to search—whereupon Uexhkull has him kill the second-in-command and go to the search.

"He put every ounce of command he could into his voice, hoping that whoever was down there would have the sense to respond."
 * Robert A. Heinlein, being an ex-navy officer, brought this up a number of times in his books.
 * Starship Troopers has two examples. First he gives a historical example: during the capture of the Chesapeake by the Shannon, a midshipman was technically in command when it surrendered, but got cashiered for desertion because he had gone below deck. Then he explains a possible case where a third lieutenant (cadet/ensign) could end up commanding a division, and notes that "you'd buy the farm" if it happened.
 * Also, someone mentions an offstage example where a junior officer was in command of a brigade.
 * He also wrote a book around this trope, Starman Jones. The eponymous character signs aboard the passenger liner Asgard as a steward (and has to forge papers to get that position). He gets a position as apprentice astrogator because of his ability and because the ship is badly short-handed in astrogation. At the end of the book he winds up as captain because the original captain, astrogator and assistant astrogator have all died and only an astrogator can hold command of a spaceship that is underway.
 * In Heinlein's "If This Goes On—", John Lyle, a junior officer in the rebel forces attacking the Prophet's capital of New Jerusalem, is thrust into the position of commanding the whole force, when his commanding officer is wounded and his tank-analogue seems to be the only one in effective communication with all the others. Lyle isn't technically next in the chain of command (he's a staff officer/aide de camp for the commander, doubling up as tank commander). However, he doesn't trust the next in line to handle the situation (too cautious) so he continues to issue orders in the commander's name, even though the commander is out of contact. Once things reach a "safe" state, he tells the real next-in-line "you are in command now".
 * And in The Moon Is a Harsh Mistress the Everyman narrator, Manny Davis, ends up in control of the Lunar Revolution's government  when the rest of the Lunar government are killed by Earth's bombing.
 * The book Spaceship Medic by Harry Harrison deals with this scenario. The eponymous medic ends up in charge after all the rest of the ship's officers are wiped out by a meteorite hitting the bridge (then has some adventures, saves the day, and goes back to being a doctor).
 * Happens at least once a book in Honor Harrington: the flagship of a formation is destroyed, or battle damage kills the captain of a spaceship. Sometimes things work out fine; usually they don't. In each example, David Weber spends at least a paragraph explaining why it is that this person is now in command, instead of the higher ranking/more qualified personnel on the next ship over (or even in the next room). The results are not always pleasant, but the logic is always sound at the time.
 * He also uses this with the short story "Ms. Midshipwoman Harrington". The eponymous character gains command due to the battle, controls the situation, and emerges victorious. She is later given a promotion earlier than normal, but only to Ensign instead of several or more ranks.
 * Most plot-relevant to the entire series is Honor's assumption of command at First Hancock in The Short Victorious War — already flag captain, she commands the task group when the admiral is incapacitated, despite not being the senior remaining officer. She's vindicated (winning the personal approval of the Queen, no less), but the fallout from that one action sets the stage for the following novels Field of Dishonor and Flag in Exile.
 * Not just in the Honorverse; examples abound in David Weber's other books.
 * In the stand-alone novel In Fury Born the protagonist Alicia DeVries gets one of these when her unit is shattered during the Shallingsport operation. She begins as a sergeant first class, leading a squad, and less than ten minutes after the battle starts ends up in command of her entire company. Then again, her company in the same span of time goes from a full complement of 275 troops to 63 survivors (they drop into what was supposed to be a clear LZ, in what was supposed to have been a surprise raid... and land right on top of a dug-in enemy battalion with heavy weapons that knows they're coming, and has been waiting for them).
 * In his Empire From the Ashes trilogy, main character Colin MacIntyre goes from mid-21st century space survey pilot to captain of Dahak, a super-advanced moon-sized Cool Starship from Talk about a serious promotion!
 * In To Say Nothing of the Dog by Connie Willis, the overworked Oxford time-travel department ends up being run in large part by T.J., an undergraduate with the wrong major, while everyone else is out on assignment in the past (he's the only black person on the staff, and all the parts of the past they're interested in are too dangerous for him). Mr. Dunworthy, the head of the department, tells T.J. the (entirely fictitious) story of Ensign Klepperman, who ended up in command of a ship during the Battle of Midway when the entire bridge crew was killed, sunk two destroyers and a cruiser, and was eventually killed in the line of duty.
 * In Diane Duane's Star Trek TOS novel Doctor's Orders, Dr. McCoy is given the con during a First Contact mission as part of a joke by Kirk. Then Kirk disappears into a temporal anomaly, a Klingon warship shows up, and Starfleet regulations won't allow McCoy to hand over command to any line officer until relieved by Kirk or Federation brass. Which means he's stuck in command in the middle of a major crisis with everyone's lives depending on his command training (which he does not have) and military ability. He does well enough that upon learning that that he was the ship's physician, the Klingon captain remarks that he needs to kill his ship's physician if they were all like like McCoy — Klingon Promotion being what it is. McCoy then tells him there's more than one reason; based on McCoy's diagnosis of the Klingon's health either his physician is outright incompetent, or is already trying to gain command of the ship by giving him substandard care.
 * Invoked in John Hemry's A Just Determination; a limited duty officer points out to an ensign that the ensign might find himself in command while just an ensign to persuade him that his testimony would be taken seriously at trial.
 * Bill Mauldin drew a cartoon during World War II on this topic: two privates are using crates as desks in a lean-to "orderly room." One is talking on a field phone, saying, "Yes, we've sent our quota to the rest camp.... This is the company commander speaking!"
 * In Sandy Mitchell's Ciaphas Cain novels, Jenit Sulla is promoted to captain because when another company lost its captain, none of the lieutenants took the initiative to lead them all in his place, whereas Sulla had taken command of her company after Captain Detoi had been wounded in the same action.
 * The Lieutenant in L. Ron Hubbard's Final Blackout is the embodiment of this, stubbornly refusing to relinquish command of what is left of his brigade in World War III (which is regarded by those who care as a later "phase" of World War II), and goes on to take over England.
 * In On the Beach, we are told that, following nuclear exchanges in World War III, "command got down to very junior officers indeed". Mentioned in Major Chan Sze Lin as being in command of what was left of the Chinese strategic forces when the Australian Prime Minister contacted him in a last ditch attempt to salvage some of the world.
 * Warhammer 40,000 novels:
 * Dan Abnett
 * Titanicus. Cally Samstag finds herself in charge of the remnant forces of activated 26th, a third line unit reduced from over 60 members to 18 in one engagement, with every officer dead. Erik Varco represents something of an inversion to the trope: he leads his battered remnant armour squadron because he was already in command when a traitor Warlord Titan annihilated them.
 * Horus Heresy novel Legion. Chayne's Backstory included becoming the leader this way of the band of Child Soldiers of which he was a member.
 * William King's Space Wolf novel Grey Hunters. Ragnor finds himself in a position to attack some enemies from behind, and relieve some hard-pressed Space Marines. He launches the attack and orders them to follow his flare to escape. They obey, and then he is told that the force includes Berek, the commander of their entire mission. Fortunately, while Berek is a bit of a Glory Hound, he is just; he praises Ragnor's quick thinking and says he is grateful (in fact, it leads directly to his Field Promotion).


 * In Graham McNeill's novel Storm of Iron, finds himself in command. When he looks at the men coming to his first briefing, he is still trying to assimilate that it is his regiment.
 * Ben Counter's Soul Drinkers novel Chapter War. After Varr's death, Kullek takes command of the 901st Regiment. He tells the Howling Griffons that the chain of command was none too clear.
 * Horus Heresy novel Galaxy In Flames. Saul Tarvitz assumes command of the space marines; Graham McNeill's Fulgrim recounts how Captain Demeter, offered the command when he recovered from his injuries, refused to take it.
 * Tavi in Jim Butcher's Codex Alera series finds himself in command of the First Aleran Legion when an enemy attack leaves him the sole surviving officer who can command. He goes from being the Third Sub-Tribune to the Tribune Logistica (the lowest possible officer rank, whose duties to that point consisted mostly of latrine-digging (a position he never even earned, being appointed there for intelligence-gathering purposes) to commander of a legion. He does far better than anyone else could ever have hoped to.
 * In Dudley Pope's Ramage, at the very start of the book, the main character finds out that every senior officer has been killed making him the captain of a frigate... which is badly damaged, sinking, and under attack by a superior enemy vessel.
 * In Jack Campbell's The Lost Fleet:
 * In an interesting use, John Geary finds himself in command of the Alliance space fleet by virtue of being the most senior captain after the higher-ups are all killed. Interesting because he got the promotion 100 years ago and, it was believed at the time, posthumously. The fact that he was even there to receive command was dumb luck when the fleet picked up his stasis pod on the way to battle.
 * Colonel Carabali also gets this when the Marine general is killed with the rest of the leadership.
 * In F.M. Busby's Zelde M'Tana, the eponymous character comes on board a starship as part of a slave cargo. Due to a mid-voyage mutiny, a relationship with the new captain, some dramatically convenient casualties, and, to be fair, a whole lot of work on her part, she winds up in command. And then they have to send her away as soon as the XO is well enough to replace her, because while she's done a good job, there would be too much resentment from the ranks to keep her on.
 * In the Wheel of Time: "When we Shienarans ride, every man knows who is next in line if the man in command falls. A chain unbroken right down to the last man left, even if he's nothing but a horseholder. That way, you see, even if he is the last man, he is not just a straggler running and trying to stay alive. He has the command, and duty calls him to do what must be done."
 * In the Dragonlance Chronicles this happens several times to the young elven princess Laurana. Sturm Brightblade puts her in command of the Solamnic Knights defending the High Clerist's Tower . And after Laurana saves the tower, Lord Gunthar Uth Wistan gives her command of his entire army. This is especially remarkable since the Solamnic Knights believe women should Stay in the Kitchen, but as most of the Solamnic leaders were killed at the High Clerist's Tower, Gunthar realizes that Laurana is the only person left with the brains, charisma, and guts to successfully lead his troops.
 * In World War Z, Philip Adler is promoted when his commander is accidentally shot with a Solanum-infected bullet. Adler's first job is to kill his commander before he turns.
 * Star Wars Expanded Universe:
 * In The Thrawn Trilogy, Pellaeon is revealed to not have been a full captain at Endor, receiving a You Are in Command Now promotion when his captain was killed... and that he, as the survivor with the highest rank, was the one who sounded the retreat. Due to various retcons, Pellaeon now was a full captain at Endor; it's just that his ship was commanded by an admiral, so he was still second in command until said admiral was killed.
 * At the end of the trilogy, when Thrawn dies, Pellaeon takes command of the fleet, and several books set later have him reporting to or working with various high-ranking Imperial villains of the book; he always survives their inevitable deaths, and since he's actually very competent he becomes Supreme Commander of the Imperial Fleet by the Hand of Thrawn duology. That's somewhere between Thrawn's and Vader's level of authority. That's right, Pellaeon becomes the most powerful man in the Empire, or what's left of it, by being unspectacularly good at his job and surviving everyone who outranked him. It does take years and years of work — he's in his 60s in the Thrawn trilogy.
 * In The Fifth Elephant, Sgt. Colon finds himself in command of The Watch after ALL his superior officers head to Überwald. It rapidly goes pear-shaped, to the point where Colon provokes the first Watchman's strike.
 * In Valiant, Michael Jan Friedman has a certain Second Officer Jean-Luc Picard (who would have held the rank of Lt. Commander at the time) on board the Stargazer. Captain Daithan Ruhalter and First Officer Stephen Leach are killed and critically injured, respectively, suddenly forcing Picard into the position of temporary CO. He doesn't exactly have an easy time of it, but since future canon has him as the Captain of the Stargazer, he eventually gets a two-grade jump to Captain.
 * In Poul Anderson's After Doomsday, Lieutenant Howard after the captain and first officer are killed. He's so ineffectual that Donnan, by acting as The Leader, takes over.
 * In Michael Flynn's The January Dancer, Hugh finds himself The O'Carroll, and leading the loyalist side, because he happened to be out of town during the coup.

Live-Action TV

 * A frequent occurrence on Star Trek:
 * The very premise of Star Trek: Voyager is that the original Starfleet crew is blended with the absorbed Maquis, and three members of the main cast receive their positions following the catastrophe that created that situation; the EMH arguably gets promoted to the status of sentient being as the result of this trope. This also occurs in several individual episodes:
 * The episode "Displaced" has the crew being abducted one by one, thus forcing everyone else to pick up the slack. Suddenly a VERY young ensign is the Chief of Security. In a bit of gallows humor Chakotay jokes, "Who said there was no room for advancement on this ship?"
 * The Doctor commanding Voyager all by himself in "Workforce" when the crew has to evacuate.
 * And "One", where the Doctor and Seven of Nine are the only crew members not in stasis.
 * "Course: Oblivion" has the crew being afflicted by a strange disease one by one, which causes this trope when the higher-ups get affected.
 * At least four Star Trek: The Next Generation episodes:
 * "Disaster" puts Troi in command, as the most senior officer left on the bridge during the eponymous disaster (despite the fact that she has no command training, which gets addressed in a later episode).
 * "Descent" leaves Dr. Crusher in command of a skeleton crew while everyone senior to her had off-ship duties. Unlike Troi, however, Crusher had taken and passed the Bridge Officers' Test, and actually enjoys command, as she would later get command of the medical ship USS Pasteur (in an Alternate Timeline).
 * "The Arsenal of Freedom" has Geordi in command, and puts him in conflict with the more senior Chief Engineer Logan. When Logan tries to pull rank, Geordi states that he is in command until he is relieved by either Captain Picard or Commander Riker. This is Truth in Television, as Geordi would be considered the Officer of the Deck as delegated by (and thus may only be relived by) the captain or XO.
 * "Remember Me" has Dr. Crusher quickly ascend the ranks as everyone else on the ship ceased to have ever existed in the local universe.
 * In the "Deep Space Nine" episode "Valiant", during a training mission, all the training officers leading a group of cadets are killed. The cadets assume command of the ship and the mission.
 * The Star Trek: The Original Series episode "Catspaw" left Assistant Chief Engineer DeSalle in charge of the Enterprise while all the higher-ranking main characters explored the surface. Over the course of the series, DeSalle appeared in a grand total of 3 episodes. Robert Bloch's original script had everyone senior to Uhura off the ship, and left her in command, but Executive Meddling wouldn't allow for a black woman being put in command of the Enterprise.
 * This tends to happen a lot in 24.
 * Except for seasons 1 and 3, Jack is never actually working for CTU. Nevertheless, by the half-way point of the first episode, the situation is already dire enough that Jack is put in charge.
 * In season 2, Tony Almeida takes over after George Mason steps down.
 * In season 4:
 * Charles Logan takes over as President of the United States following a semi-successful assassination attempt on the standing president.
 * Tony is catapulted from unemployed ex-con drinking beer out of a Cubs mug to acting director of CTU within a span of about four hours.
 * In season 7, Renee Walker takes over the FBI's operation following the death of her boss.
 * In season 8, Chloe O'Brian jumps from a token hire to head of CTU. In the same episode, Dalia Hassan goes from widower to President of Kamistan.
 * Castiel from Supernatural goes from an angelic foot soldier (albeit a high-ranking one) in Season 4 to the "sheriff of Heaven" in Season 6 when all the archangels have been killed and imprisoned. He then battles with Raphael, the last remaining archangel, for control of Heaven.
 * In the episode where the brothers are sent back in time to the Wild West, Dean and the innkeeper find the sheriff's smoldering corpse in one of the rooms. Dean asks who the new sheriff is, and the innkeeper pulls the badge off the corpse and pins it to Dean.
 * In The Young Indiana Jones Chronicles, Indy and Remy go from private to captain and lieutenant in the Belgian army while serving in World War I, mostly by this method.
 * Hawkeye has to take command of the eponymous unit in MASH several times during his stay in Korea. It always ends badly. Then there's Frank Burns—which is worse. The only temporary commander of the 4077th that is tolerable is Major Winchester, and that's because he uses his times in command to loaf (and doesn't interfere with day-to-day operations).
 * In the re-imagined series of Battlestar Galactica, virtually the entire military sees this trope in action.
 * Bill Adama, old warhorse ship's captain about to be put out to pasture, finds himself in command of the entire Colonial military, what's left of it. All sorts of people who previously filled fairly minor roles are suddenly thrust into positions of great authority... in many cases, they're doing the same jobs they did before, but those jobs are now of critical importance because there's nobody else doing them. For that matter, the eponymous Battlestar is itself promoted from "antique vessel about to be mothballed" to "flagship of the Colonial battle fleet." (Also only ship of the Colonial battle fleet, but that's par for the course with this trope.)
 * After the deaths of Admiral Cain and Colonel Fisk, there's no-one to take command of the battlestar Pegasus, so Admiral Adama appoints Barry Garner, an engineer, as its commanding officer. This doesn't work out very well, as Garner treats the crew more like parts of a machine than as human beings and jumps straight into a Cylon trap.
 * This again happens when Garner leaves the CIC during an intense battle to fix the FTL drives, telling Lee that "you have the conn". Lee gets promoted to full commander at the end of the episode.
 * In the finale, Lt. Hoshi is later promoted to Admiral in the wake of a mutiny led by the man who otherwise would have got the job had he not snapped, and everyone else that would have stood between him and the position had also been killed off by that point. Not a bad finish for the guy who entered the series as the guy standing in the corner looking utterly mortified while Admiral Cain orders an attack on Galactica.
 * Hoshi is only really in command of the civilian ships and whatever military units are left when the Galactica goes off on its final mission. There are still plenty of more senior officers but they are all going on the mission. His new rank will not become effective until they are all killed (very likely at that point). At this point the military rank structure is shot anyway and being competent and loyal gets you the job.
 * Laura Roslin falls under the civilian version of this trope, Unexpected Successor. Please don't list her here.
 * On 3rd Rock from the Sun, Sally was next in command after Dick. In one episode, both Dick and Sally were incapacitated and Tommy assumed the role of High Commander (with only Harry left to command).
 * Stargate Atlantis has had several promotions by death of senior officers, including Major Sheppard becoming the military commander of the expedition, and Dr. Keller becoming the chief medical officer.
 * It's not stated in the series itself, but Shepard would have needed several of these in his backstory or he would have been too young for his starting rank.
 * In the prelude of Firefly, Malcolm Reynolds, a sergeant, ends up in command of all the ground forces in the Battle of Serenity Valley. When one of his men says they need an officer's authorization to get air support, he tears a patch off a dead lieutenant and hands it to the trooper, congratulating him on his promotion.
 * By the beginning of season five, in the episode "Holoship", Red Dwarf's Rimmer states that he has been in command of Red Dwarf since Lister was revived.

Videogames
"Yellow Squadron pilot A: Oh! Jean-Louis' been hit! Yellow Squadron pilot B: Gene, get a grip! You've got to take over the command!"
 * If you choose the Lawful story arc in Neverwinter Nights 2, your character goes from new recruit city watchman, to lieutenant, to squire, to Captain of Crossroad Keep, to Knight-Captain of Crossroad Keep in under a week, due to the death by burnt-down-headquarters of the former holder of the first post and the suddenly increased importance of the fortress in the second post. It also helps that by that point you practically single-handedly rein in crime in the city and win Neverwinter a war.
 * Gears of War has the soldier Marcus, convicted of abandoning this post and branded a traitor, getting a field promotion when the commanding officer dies. This is a case of practicality: Marcus is chosen because, despite his treason, he is still hands down the best, most qualified soldier in the squad, despite being absolutely hated by the Gear commander. Dominic, Baird and Cole all follow Marcus not because he's in charge, but because he knows what he's doing. Baird initially puts up some resistance, but even he comes to see the wisdom of having Marcus in command.
 * Greil of Fire Emblem: Path of Radiance begins putting his son Ike in command of their mercenary force during missions as soon as Daein invades Crimea near the beginning of the game. The implication is that Greil anticipated his own death in the war that was sure to come, and wants his son to be prepared to take command for real in that event (he's completely right in this). A dialogue between Titania and other members of the Greil mercenaries tells us later that Greil always wanted his son to become the leader of his mercenary unit: had the war not happened, Ike would have become their leader eventually, just later.
 * Ace Combat:
 * Temporarily averted and subverted in Ace Combat 5. The player character is originally just whatever the fighter pilot equivalent of a grunt is, but then The next mission, Nagase is assigned command of the squadron, as she's currently the most experienced in the squad. She turns the command down, giving it to the player. The mission after that, a new squad commander is sent by the Osean Air Force.  Player character Blaze eventually becomes such a respected flight lead that a man with years more experience is happy to follow his lead.
 * Subverted in Ace Combat 6: One of the antagonists, Victor Vocheck, took part in the initial invasion and takeover of the player's capital city, Some of his subordinates assume command of his squadron until they got shot down by the player character. The situation becomes so bad, that the squadron had to consolidate with another squadron who is put under the command of Vocheck's protege,
 * The final mission of Shattered Skies gives us this exchange from the pretender Yellow Squadron pilots:


 * Also, if you manage to down the Yellow Squadron pilots in the right order (something nearly impossible to do, as there is no way of differentiating them), the dialogue continues as the pilots' command structure disintegrates and pilot B gets command, then C...


 * In the 2008 Turok video game, thanks to rapid character attrition, the Redshirt Army is soon reduced to several grunts and a sergeant. Said sergeant promptly takes command, which turns out pretty badly for everyone else, as he's slowly going bonkers due to a head injury.
 * In squad-focused games like Battlefield 2, fickle internet connections can cause the most senior squad member (by global score/rank) to assume leadership should the original leader be dropped from the game. Sometimes results in a Hot Potato among the remaining squad, who likely joined so they wouldn't have to command.
 * Happens a few times in Command & Conquer, notably with Nod. The best example would be in the original; Seth is (heavily implied to be) trying to get rid of both the player, a Nod commander, and Kane, Nod's leader. Kane puts a bullet through his head, recalls the player's troops, gives you a new assignment, and ends with "Oh--And congratulations on your promotion." as he looks down at Seth's corpse.
 * In Final Fantasy VIII, Squall Leonhart finds himself summarily shoved into command of the entirety of Balamb Garden, though in this case it's because of a combination of Garden's role changing from "military academy" to "active fighting force" and a case of You Can't Fight Fate: . Considering that Squall is an emotionally stunted seventeen-year-old and wants to be in charge about as much as he wants a hole drilled in his head, it goes pretty well.
 * In Wing Commander IV, Colonel Blair finds himself in this position aboard the Intrepid when Captain Eisen leaves for Earth to reveal plan, even though he's Space Force and not Navy. Somewhat subverted in the Novelization, in that he was assigned a Lieutenant from the Navy who was too junior to promote to Captain (rank, not position) to give the actual commands for carrying out Blair's orders. In the real world, aircraft carrier captains must themselves be part of the aviation community (i.e. have been a naval aviator themselves).
 * Even in video games, Star Trek ventures into this territory:
 * In Star Trek Online, this is how the player becomes captain of their own ship, starting off the game as an ensign. The ship in question is a small one with a crew of ~50 or so, and it's specifically noted that the Borg who boarded it while the player was assisting another ship wiped out the officers first, leaving the player as the *only* surviving officer of that crew. (This is also noted as unusual behavior by the Borg and eventually explored later on in a high level mission.)
 * On the Federation side, once the player reports in to Admiral Quinn to get his battlefield commission formalized, the Admiral outright admits that they've been reduced to this by how pressed Starfleet is to deal with their various border conflicts.
 * This is mentioned twice in the backstories for the teachers in Star Trek: Klingon Academy. One of them was due to a vacancy that the man created himself via Klingon Promotion. The other was briefly Captain of his ship on the grounds that he was the seniormost officer on the bridge when the original Captain died, and then surprised the first officer (who was busy elsewhere when the Captain died) by turning command over to him at the battle's end instead of attempting a Klingon Promotion.
 * In the cutscene of the first World in Conflict mission, we see our soon-to-be-least-favorite commander driving through the streets of Seattle which is being attacked by the Soviets, trying to reach the commanding officer in charge of the defense on the radio. "Well, who is in command then? What do you mean, 'I am'?"
 * Warhammer 40000 Space Marine: Second Lieutenant Mira Nero is the highest ranking officer left on Graia, and will remain so unless her superiors suddenly rise from the grave. In her own words; So far, they seem content to stay put.
 * Optimus Prime in Transformers: War for Cybertron is forced to take command after Zeta Prime is defeated. None of the Autobots see this as a bad thing (and seeing how Zeta Prime had a We Have Reserves attitude and Optimus doesn't, it's no wonder that the Autobots are happy Optimus is in charge).
 * In Shin Megami Tensei: Strange Journey, you are summarily promoted to mission commander when from that point on, all crewmen will follow your lead. Even Arthur, your ship's artificial intelligence, will only issue missions to you and advise you as best as he can based on his role as mission analyst, but doesn't actually have any authority over you. It gets to the point when.

Webcomics
"Tempo: ... further, in consideration of your status as commander of a foreign vessel, I recognise you as military attaché for your mission, with the right to be addressed as captain. Jardin (thinking): I hadn't until then realised, as last survivor, I was technically Bellarmine's commander."
 * In Outsider, Ensign Alexander Jardin finds himself in command of his ship due to being the Sole Survivor.


 * Gil causes this trope in an attacking army in this Girl Genius.
 * From Order of the Stick: "Have a nice day, and thanks for the promotion."
 * In Impure Blood, the council has no superiors, so Dara seizes command because the situation's about to become military.

Western Animation
"Zapp: (After steering the ship towards a black hole) Nothing remains now but for the captain to go down with the ship. Kif: Why, that's surprisingly noble of you sir. Zapp: No, it's noble of you Kif! As of now, you're in command. (Rips insignia off his arm and sticks it on Kif) Congratulations Captain. Exits room and is soon seen outside fleeing in an escape pod."
 * On an episode of The Simpsons, Homer ends up in command of a nuclear sub after the Captain tells him that he is in command until he gets back. The Captain is then accidentally launched out of a torpedo tube. By Homer.
 * Parodied in Futurama, when this exchange took place:

"Black Mask: You. You're my new Number One."
 * Black Mask in The Batman tends to kill off his second in command about once per episode, and point to a random underling proclaiming:


 * The Big Bad in Sym-Bionic Titan does this after killing the alien when he has a You Have Failed Me... moment.
 * In the Star Trek: The Animated Series episode "The Lorelei Signal", all the male members of the crew are incapacitated. Uhura takes command of the ship and leads a landing party to rescue the male senior officers with Nurse Chapel as Chief Medical Officer and second-in-command. Uhura is never actually given command, and her commandeering the ship is technically mutinous (and she justifies this in the ship's log), but her superiors commend her actions once she rescues them. She also gets left in command in "Bem" when Kirk, Spock, Scotty and Sulu are all part of a landing party.

Real Life

 * Band of Brothers (Reference: book by Stephen Ambrose and the mini-series):
 * When the Battle of the Bulge begins all the higher ranking officers of the division are absent. When one of the officers starts complaining about this, the ever-competent Major Winters quietly tells him to concentrate on organising his men and finding ammunition and winter clothing for them, instead of wasting time waiting for superiors who might never turn up.
 * Dick Winters does this several times throughout the war. He drops into Normandy as a 1st lieutenant in command of a platoon, but ends up commanding the company because his CO is MIA (turns out, the CO never even set foot in Normandy - his plane blew up on the way). Later, when Major Horton is killed during Market Garden, he becomes battalion XO.
 * Some time after he becomes Battalion XO and while he's still a captain, Winters acts as 2nd Battalion CO while Strayer (the actual CO) performs the duty of an absent Regimental Officer. This results in Winters having to contend with going up against the 1st and 3rd battalion COs, who are both lieutenant colonels, when it comes to acquiring resources for both the missions to which his battalion gets assigned as well as provisions for his men.
 * At Pearl Harbor:
 * The USS Aylwin (DD-355) had four officers on board when the first Japanese aircraft appeared, all ensigns. Ensign Stanley B. Caplan, the senior one, had been at sea for only eight months and was in command of it for thirty-six hours (ironically enough, as he was obeying orders from the destroyer squadron commander to put out to sea, several men onboard saw their senior officers on a motor launch, but they could not stop to take them onboard until after the attack was over).
 * The same thing happened to USS Blue; again only 4 ensigns were on board (must have been the standard officer duty section) and they got underway and operated for 30 hours with an ensign in command, attacking two submarines and shooting down 5 Japanese airplanes.
 * During the Japanese occupation of the Philippines, American soldiers who escaped capture took command of local guerrilla groups and promoted themselves to the rank appropriate for the size of their band. For the most part, the US military honored these self-made ranks after the war.
 * In the Age of Sail this trope could often apply to members of the British Royal Marines. Lieutenants often ended up commanding landing forces whose size would call for people several ranks above them despite the presence of naval officers of suitable rank joining their force. They were trained for it, unlike the naval officers, and a lieutenant was the highest-ranked marine officer you'd normally find in the fleet.
 * The Ten Thousand: in 401 BC a force of Greek mercenaries is hired by Cyrus the Younger to supplement his Persian troops to fight against his brother Artaxerxes II for the throne of the Persian empire. They meet at the battle of Cunaxa. While the Greek force suffers no significant casualties during the battle, their employer, Cyrus, is killed during the battle.They are then left stranded in the middle of the Persian empire. They are asked by the Persians to lay down their weapons but they refuse. The leaders of the Greek are invited to a feast to negotiate a solution but are instead executed. The Greek elect new leaders, among them Xenophon who chronicle their fighting retreat through Persia which lasted around 2 years.
 * In the Soviet Red Army, especially during World War II, this happened frequently. Interestingly, their system was set up so an officer usually had to serve a given number of years in a rank before being promoted to the next one and they saw no particular reason to change the rule even if the officer in question was, through attrition, leading a much larger unit than he'd started with. If the officer was competent he was allowed to retain command and sometimes even promoted to a higher one while retaining the rank, thus leading to captains leading companies reporting to a lieutenant who led the battalion, while the regiment might be commanded by a captain who had several majors as his subordinates.
 * On the first day of the ANZAC invasion at Gallipoli, Turkey, lack of planning meant a lot of the soldiers just lost track of their commanding officers, if they were "lucky" enough to even get to the beaches, so this trope happened all over the place, for the unprepared Australian and New Zealand soldiers.
 * Peter Lalor, an Australian soldier is said to have seen that there were no officers for his battalion, the 12th, gave the rousing order of "Come on, the 12th" and charged at the Baby 700 Hill. He died.
 * During the American Revolution and the War of 1812, the British wore, like everyone else, Bling of War, especially their officers (even though the Americans were no different in this regard). The Americans, used to hunting, could aim (even with muskets, even though they had to get very close to do so), and would chose the most visible targets. As a consequence, after the Battle of Bunker Hill and the Battle of New Orleans, certain British regiments were under the command of the senior private.
 * In the last days of World War II, Hitler's most powerful underlings who were not in Berlin, Hermann Göring and Heinrich Himmler, attempted to take control of the crumbling Third Reich and negotiate peace with the Allies respectively. Outraged at the supposed betrayal of his own designated successor (Göring) and his most loyal follower (Himmler), Hitler banished both of them from the Nazi Party and prepared for his suicide. In his last will and testament, he named Karl Dönitz, the commander-in-chief of the Kriegsmarine, as President and Joseph Goebbels as Chancellor. Shortly after Hitler's suicide, Goebbels killed himself as well, leaving the leadership of Nazi Germany (or what remained of it) in the hands of an Admiral who almost single-handedly crippled his own submarine campaign. The reasoning behind selecting Dönitz was because, in Hitler's mind, the Kriegsmarine had failed him the least.
 * An even more egregious example: The new Reichfuehrer-SS was Karl Hanke, Gauleiter of Silesia. A fine choice, where it not for the fact that he was trapped in Wroclaw, nearly 200 miles into Soviet territory, surrounded by the Soviet 6th Army.