Remember the Alamo!

""Every society needs a cry like that, but only in a very few do they come out with the complete, unvarnished version, which is 'Remember-The-Atrocity-Committed-Against-Us-Last-Time-That-Will-Excuse-The-Atrocity-That-We're-About-To-Commit-Today! And So On! Hurrah!'""

- Thief of Time

A Battle Cry that memorializes an enemy atrocity and is invoked to galvanize the civilian population into supporting the war effort. Historically, an alternate title might well be Remember the Maine!.

Perhaps a Discredited Trope in works set in the present day or near future. Subtrope of Shocking Defeat Legacy.

Anime-Manga

 * ZAFT soldiers in Gundam Seed and Gundam Seed Destiny often reference the Junius Seven tragedy in their war cries.
 * Full Metal Panic uses "Remember Pearl Harbor"- said by the captain of the USS Pasadena. It results in his Japanese-American XO facepalming in despair.

Literature

 * In James Blish's sci-fi Cities in Flight stories, it's "Remember Thor V!"
 * V is the Roman numeral 5. Thor V is thus the fifth planet of the Thor system. The organization known as Interstellar Master Traders committed unspecified atrocities there.
 * The rallying cry lasted for many decades, if not centuries, due to anti-agathic (anti-aging) drugs.
 * Mayor Amalfi of New York City met up with IMT in another galaxy, whence they fled. He shouted this to panic their leaders into an ill-considered act. He's surprised when not only the leader of IMT blanches, but many of his guards as well.
 * David Drake and Eric Flint's Belisarius Series.
 * Ethiopian warriors shout "Ta'akha Maryam!" when attacking the Malwa forces. The Malwa assassinated the Ethiopian king at Ta'akha Maryam, before war was even declared.
 * Persian forces use "Charax!" as a battle-cry, after the Malwa massacred the civilian population of the Persian city of Charax.
 * And even more so, after Belisarius's troops take the city back and it's discovered that the civilians that were slaughtered were the lucky ones.
 * Discworld - Terry Pratchett translated it as "Remember the atrocities the enemy has done to us, for they will justify the atrocities we are about to commit today" In Discworld, it was usually "Remember Koom Valley!"
 * Unusual in that it was invoked equally by both sides of the conflict.
 * Because it's the only battle in history where both sides ambushed each other.
 * It's also enduringly popular, being used in wars across history and indeed even those nowhere near Koom Valley. This is because the History Monks patched it in all over the place as the 'generic atrocity' when they rebuilt history.
 * Made all the more tragic when it's revealed
 * The Fremen saying in the Dune series: never forgive, never forget.
 * In The Wheel of Time, many of the main characters are from a town that stands over where the ancient city Manetheren once stood. The city was completely and utterly annihilated and that battle is often recalled to inspire them to continue fighting the enemy Trollocs.
 * In Echoes of Honor: the Grayson commander uses "Lady Harrington, and no mercy!"
 * Also from David Weber is A Mighty Fortress, the fourth book of the Safehold series, in which a fleet buying time for what ships can get away uses "Remember King Haarahld" as its battle cry, in memorial of their late king's Heroic Sacrifice.

Film

 * Dog Day Afternoon - "Attica!"
 * From Dune Taqwa!
 * American Werewolf in London has this as the punchline of the joke told by Brian Glover in the Slaughtered Lamb.

Newspaper Comics

 * Parodied in The Far Side: A soldier cries out: "Remember...uh, remember that place in Texas!"
 * Also parodied in, of all strips, Steve Canyon: Steve was having a dream, chock-full of anachronisms, about being part of Perry's 1850s expedition to open up Japan. When a quarrel with the local authorities began, he suggested the ambassador say "Remember Pearl Harbor!" as a "So there!" The ambassador used it and then asked Steve, "Where the heck is Pearl Harbor?"

Tabletop Games

 * During the First Succession War of Battle Tech's Backstory; the Draconis Combine had the Federated Suns on the brink of defeat. However when their ruler was assassinated by a Sun's sniper on the planet of Kentares IV (as a legitimate military target) his son and successor had 90% of the planet's population, roughly fifty two million people, executed in cold blood. The atrocity rallied the Federated Suns, who used "Remember Kentares!" as a Battle Cry, and cost the Combine its previous gains.

Video Games

 * In System Shock 2 "Remember Citadel", the setting of the first game, is daubed on the walls with blood.
 * It's somewhat less of a battle cry and more of a warning that you can't trust Xerxes, the AI that controls the ship.
 * Parodied in Ty the Tasmanian Tiger with Boss Cass who tries to steal the MacGuffins with a cry of "Remember the Comet!" (referring to the comet that wiped out the dinosaurs).
 * In Halo: "Remember where it all began. Remember Reach!"
 * Before Reach, it was "Remember Harvest!"
 * A variant of this is used by the Terra Firma protesters in the first Mass Effect game, who, at their annual protest, shout "Remember Shanxi!" - Shanxi being the human colony that was almost destroyed by the turians during the First Contact War. Trying to incite aggression towards the turians in this way is in line with their policy of ceasing or at least reducing cooperative relations with the Council races.
 * In World of Warcraft: "Remember the Sunwell!"

Web Originals

 * Digger: Remember Tunnel 17!
 * The Onion urges us, in the spirit of Politically-Correct History, to Misremember the Alamo.

Real Life

 * Remember remember, the 5th of November in 1605.
 * During the Texas Revolution in 1836:
 * "Remember the Alamo!" - The massacre at the Alamo on March 6, during the Texas Revolution.
 * "Remember Goliad!" - The Mexican massacre of prisoners at Goliad on March 27 during the Texas Revolution.
 * Both of these were used as battle cries during the Texas victory over the Mexican Army at San Jacinto, April 21. Making the Battle Cry version Older Than Radio.
 * "Remember the Maine" - The sinking of the U.S.S. Maine in Havana Harbor in 1898 helped spark the Spanish-American War.
 * The battle cry was popularized before the investigation even started. It is generally agreed now that the Spanish weren't actually responsible.
 * Not really the point.
 * "Remember the Lusitania!" - the sinking of the British ocean liner (auxiliary cruiser) in 1915 helped turn world opinion against Germany in World War I.
 * As with the Maine example above, some historians think the Lusitania was either carrying weapons or was pretty much a bait (either by Great Britain or America) to get American citizens to support American participation in the war.
 * She sailed into a declared war zone. She was also officially listed as an Armed Merchant Cruiser.
 * She was also carrying guncotton (artillery shell propellant) and fuses for artillery shells, along with 4,992 shrapnel shells.
 * The German government put up an add in the biggest newspapers to NOT board a british ship sailing into a warzone, since german u-boats might sink it. IF they board it, they do so at their own risk, and have been warned. Still it was all germany's fault, somehow.
 * That's like a schoolyard bully justifying an assault because the victim didn't give into his threats.
 * Remember that the Germans made a point of only sinking merchant ships.
 * "Remember Pearl Harbor!". The Japanese attack on the military base at Pearl Harbor, on December 7, 1941, prompted the USA's entry into WWII. Japan did not formally declare war on the United States until after the attack.
 * At Leyte Gulf the American Battle Line contained several battleships that had been salvaged and returned to duty. They destroyed the Japanese in a One Sided Battle at Suriago Strait.
 * From Snopes, an example from The War On Terror: 9-11 We Remember.
 * Another War On Terror example: "Let's roll!".
 * NEVER FORGET.
 * The American Revolution: "Give 'em Tarleton's Quarter!", meaning essentially "take no prisoners." This was a reprisal for the killing of continental troops asking for quarter by loyalist soldiers serving under Banastre Tarleton, though the reason the loyalists continued to attack may be because Tarleton's horse was shot out from under him by musket fire, giving the impression that the continentals fired while claiming to surrender.