A failed peace conference between Scotland and Norway over the custody of the Shitland Islands results in the deaths of several Scottish and Norwegian sailors (as well as one Swedish escapologist but nobody cares about him).
The future Saint Valentine goes on a wild killing spree brutally murdering every man, woman and child in his native village. Mailing the hearts of his victims to the mayors of neighboring villages. One of the mayors, Valentine's ex-wife Valerie, raises an army against her estranged husband only to fall in love with him during the battle. Oddly enough it was after the crazed Valentine had thrown his own feces at her. Women, huh ?
A particulrly vicious game of dodgeball results in the killing of hundreds. It has since been claimed that the victims were eventually ressurected as the first Zombies, which were used by the the Swiss Monarchy against the Easter Bunny.
During the Pirate-Ninja War, a group of 20 pirates and ninjas under <insert name here> are ambushed and killed in an attempt to capture Michael Iverson and a small ninja group holding out on Kawagucci Island.
In what would be the only battle to be fought during the Upper Peninsula War, a force of 2,000 Michigan Militiamen under the command of Lt. Tyler attack a small group of around 500 Canadian milita occupying the town of Rudyard. After sustaining heavy casualties, Tyler's forces begin executing the surviving Canadians and local residents.
Shortly after the publication of Alice in Wonderland, obsessed fans of the memoirs rushed to Wonderland where they began hunting the indiginous Cheshire Cats shooting at anything that moved. Within a short time, the population was greatly depopulated and the majority were forced to flee to neighboring Funderland, Sealand, Fairyworld, Crackland and Alaska. Those which remained, resorted to petty theft and crime becomiong a large part of the areas criminal element frequently attacking tourists.
A mob of angry Amish farmers burn down the neighboring city of Handlebrigsenburg in protest against the passing of a sausage-link tax recently introduced by the Pennsylvania Department of Agriculture and Commonwealth Defense.
Following a military coup outing El Salvadorian President Manzano de Tierra, an apple-led uprising under Granny Smith captures several towns and injures almost 100 people within three days before military forces wipe out the revolt exectuting between 10,000 to 40,000 apples.
After an argument with his mother, 27-year-old Jim Freklowski threw his glass sippy cup on the floor, which shattered beyond repair. Luckily, he was able to conceal the damage using a dust pan and some Brawny paper towels.
In one of the great unsolved war crimes of World War II, the bodies of over 10,000 officers of the Polish Army are found in the Katyn forest in the former Soviet Union. After decades of arguing between the Polish and Russian governments, both countries brought charges against American football player "Packman" Jones in 2003 accusing the 24-year old of sole responsiblity for the massacre and later forced to appear before the UN War Crimes Tribunal in The Hague, Netherlands. 
On the run from the FBI, the Francer-Young Party are ambushed by a group of Dark Side Mormons in the guise of Indians. Mormon leaders Karl Rove and Tony Blair are claimed to have killed at least 38 women and children single handed.
In one of the deadliest school shootings in American history, leading high school students and all star athletes Eric Harris and Dylan Klebold launch a terrorist attack against their school armed with high-powered potato guns, a sawn-off Red Ryder BB gun, slingshots, waterbaloons and semi-automatic pellet rifles wounding three teachers and killing numeous Goths before fleeing the area after self inflicted wounds from their potato guns.