Civil Warcraft

In Real Time Strategy games, the various factions are usually unified, monolithic entities. But fighting the same enemies in battle after battle gets boring. So the developers will often contrive some reason for fighting against your own side in single-player scenarios. Usually this involves betrayal on one or both sides.

Also, the campaign mode in an RTS game often serves as an introduction to the multiplayer game. So the game is obligated to not only force you to play each side, but also to contrive reasons to encounter each possible matchup. Which includes fighting your own side.

A storyline-motivated form of the Mirror Match. Compare Enemy Exchange Program and Enemy Civil War.


 * In Achron the remnants of the human fleet find themselves fighting against a section of the military that seems to have its own objectives. In the Grekim campaign one of their leaders decides he would be best to lead their race, and hunts down the others. The Vecgir end up fighting against their own when they face a group of runaways that went and joined the Grekim.
 * In Warcraft and Warcraft II, several Alliance vs. Alliance missions were centered around traitors who for some reason decided that siding with the evil Orcs was in their best interest. The Orc vs. Orc missions involved a power struggle between two major Orc leaders, Gul'dan and Doomhammer. Then, Beyond the Dark Portal came along, and everything got complicated.
 * Warcraft III had a fair bit of this as well:
 * The end of the Orc campaign involved squaring off against a camp of corrupted Orcs. Though the enemy orcs were much stronger counterparts of your own, they still matched up well enough.
 * The Frozen Throne, the expansion pack for Warcraft III, had a three way war between the Forsaken (Undead) VS. Scourge (Undead) VS. Dread Lord Rebels (Undead) missions, and a couple Blood Elf vs. Alliance missions, the Blood Elves being a visually different but statistically identical splinter faction of the Alliance forces.
 * Starcraft had this, sometimes extensively, in all the campaigns. The Terran campaigns featured widespread conflict between the various human factions and oftentimes missions involved fighting other Terrans rather than the alien invaders encroaching on Terran space. Zerg versus Zerg scenarios made more sense as they involved Zerg forces in disarray following the death of a unifying hive mind entity. The Protoss campaign however is the worst offender, with the Protoss leadership choosing to fight a civil war over a supposed heretic even as they were losing the battle to save their homeworld.
 * The Command & Conquer games have this as well.
 * The Nod campaign of Tiberian Sun starts off as a civil war between various factions of the group. Later there's a subversion where you hijack GDI equipment to fight the Forgotten (who are using Nod equipment).
 * The Soviet campaigns in Red Alert 2 and 3 necessitates the elimination of another Soviet general whom the Soviet leader has declared inconvenient to keep around. Of course it's only a matter of time before they try to do the same to you.
 * And in Red Alert 3, when playing as the Allies.
 * Red Alert 3: Uprising will have former Crown Prince of Japan Tatsu, now cooperating with the victorious Allies, going against the Japanese generals.
 * In Command & Conquer: Generals, the only faction that ever outright fights their own side in the main campaign is the GLA. Given that they're a massing of factions rather than an army of a particular country, this makes sense. The "Generals Campaign", however, pits a general of your choosing against each of the other available generals in sequence, including the ones that share your nationality. With there being 6-7 AI generals to choose from (In a non-modded version of the game, the Infantry and Demolition general levels are Dummied Out), in a campaign where 6 are randomly chosen to fight you, it is guaranteed that you will go up against someone who shares your nationality.
 * In Command & Conquer 3, Nod missions at Sarajevo and Ayers Rock involve the player Kane-loyalist Nod army facing off against rogue Nod soldiers.
 * Also done well in the Kane's Wrath expansion, the first Act involves vanilla Nod forces fighting against the Black Hand, a subfaction.
 * Command and Conquer 4 has you fighting your own faction no matter what side you choose. On top of that, the GDI campaign doesn't have you fighting renegade GDI soldiers, you ARE the renegade GDI soldiers.
 * The Warhammer Fantasy Battle World is so discordant that it actually makes sense for almost anyone to be fighting themselves.
 * The same for the Warhammer 40000 Galaxy.
 * They've now released an expansion for Warhammer in White Dwarf focusing on civil war, detailing rules for all the possible reasons a faction would have for fighting themselves.
 * Speaking of which Dawn of War Dark Crusade features two scenarios with either the Imperial Guard fighting the Blood Ravens or the Blood Ravens fighting the Imperial Guard because each has their orders concerning Kronus and neither will give ground even to their own Imperial allies.
 * And of course it happens again in Soulstorm this time between the Imperial Guard, the Blood Ravens, and the Sisters of Battle.
 * Happens a few times in Supreme Commander, either due to corruption by Seraphim artifacts or internal politics. The expansion pack goes a step further, by having the Aeon Illuminati split completely into those who join up with the Seraphim, and those who join with the UEF and the Cybran Nation to try and save humanity.
 * Notably, it isn't until the very last mission of the expansion pack that a UEF-UEF battle takes place, though during any mission, you have the option of capturing enemy units (or better still, factories), and gaining access to that tech tree. The most entertaining example this troper can think of is capturing a Seraphim factory in the fourth mission of the expansion and building Ahwassa experimental bombers.
 * And with proper preparations (a few Salvations, Experimentals or an ACU with a nuclear tactical missile launcher) the UEF-UEF battle will be one of the shortest in recorded history.
 * World in Conflict has Soviet special units take over an US base and use an absurd number of captured US vehicles in an attempt to attack New York. However, there is no chance of fighting your own faction in multiplayer.
 * Rise of Legends inverts this: most missions have you fighting an enemy using the same units as you are, or dark glass versions in the Alin campaign. Only a few missions have inter-factional warfare, and all but two amount to skirmishes.
 * The Age of Empires series has some of this, most memorably in the Montezuma campaign of Conquerors. In the second scenario, after you defeat the Tlaxcala, your allies declare war on you.
 * Barbarossa's campaign in Age of Empires II: Age of Kings. The second mission involved attacking Poland without a Town Hall. True to history, you end up betrayed by Henry the Lion twice and end up having to deal with him in addition to existing obligations.
 * It's actually very common in Age of Empires and its sequel, often when your civilization is fighting a rival state of the same civilization (e.g. Athens vs. Sparta, France vs. Burgundy).
 * The first Salah ad-Din scenario has the Egyptians start off as your friend, then declare war on you, then become your friend again when you convince them you really are only going through Cairo to go kick some Crusader asses.
 * Age of Mythology's campaigns is a series of this. The reason for this is that the only consistent units that you control are a band of heroes who are traveling the ancient world in order to, and that you raise armies from the people of where you happen to be. The villains do this as well, meaning that most battles involve the same units-the only difference being the gods worshiped by either side.
 * The expansion starts of fairly normal, but then turns into this again when it turns you've been fighting for the wrong side.
 * Of course, the main game has a dream sequence where you join the legions of Hades to fight the "Evil Empire", that being
 * In the Star Wars RTS Force Commander you're arrested, and you have to walk up to storm troopers who are more loyal to you than to the Empire in order to escape (it's the only level I can recall from the game in which there is a unit on the map to represent you). After that, you completely switch sides.
 * Completely averted in Company of Heroes, where even in multiplayer you can never fight your own faction. This holds true in the expansion pack Opposing Fronts which added two new factions that still cannot fight a civil war. In fact, in Opposing Fronts multiplayer, the Americans and British factions must always fight on the same side, as must the two German factions (Wehrmacht and Panzer Lehr).
 * Quite interestingly played with in Star Wars Battlefront II, in which one mission of the 501st's campaign involving playing as Imperial Stormtroopers fighting an army of old Republic Clonetroopers on Kamino
 * In Earth 2150, playing as the Lunar Corporation (who were allied with the UCS) had one mission where you were both on the same map fighting the enemy together when a virus corrupted the UCS programming, turning every UCS unit on the map against you.
 * In Act of War: Direct Action, it is revealed . The player then has to fight his own side.
 * In the final level of the expansion High Treason, . The game makes no attempt whatsoever to explain how this occurred plot wise, and again the player must fight his own side.
 * The Consortium has plenty of connections, merely telling a General of his division that the TFT has captured the president isn't too far of a stretch as Chamberlin was one of the Consortium members. For TFT, remember that the TFT was also forced to fight the US army remnants whom had confiscated TFT equipment while on the run.
 * Homeworld: Cataclysm has an enemy whose main weapon is an infection beam that can instantly convert your units and send them back against you.
 * somewhat averted in that larger craft sprout nasty, fungus-like nodes of beam-spewing death later on...


 * Republic the Revolution features this as a late-game mission arc - a trusted ally leaves with half your agents, and you have to erode their support to recruit them back.
 * Heroes of Might and Magic IV took this to really extreme levels when all six campaigns of the original game had the main enemy of the same faction as the player. Not so much in the expansions, though.
 * The first faction you need to destroy in Brutal Legend is an Evil Counterpart army of human slaves who refused to defect from Doviculus' rule, led by General Lionwhyte.
 * Sword of the Stars doesn't have a campaign, but the very detailed fluff makes a point of explaining how the otherwise-unified races might have multiple factions in play:
 * Far-flung human colonies attempt to declare independence, and refuse to take central command's "no" for an answer.
 * The Tarka's complex hierarchical society is highly prone to political warfare under normal circumstances, this can easily boil over into military conflict.
 * A Hiver "princess" may get too big for her boots and attempt to wrest power from the existing Queen.
 * Two Liir factions can start a conflict if each considers the other Suul'ka (roughly, "soulless")
 * Zuul are by nature territorial and aggressive, infighting of various magnitudes is common.
 * Morrigi can end up at each other's throats if two sufficiently powerful trade cartels end up vying for trade routes.