There's been lots of World Wars in UnWorld history. Here are all of them:
World War I[]
Ponies did a bunch of stuff Nobody cares about, and everyone started becoming Bronies creating a hideout and government in Germany, luckily everyone like UnAmerica and teh UnUK annihilated them and they were almost fully erased when hitler mass genocided during ww2, the war was a giant technology leap though, with new types of gas bombs being used and machine guns which were pretty cool. Tiger Tail's army got sick of the war and it ended pretty quickly after they joined. The war ended with Twilight sparkle getting merked by turtles and all the brony soldiers were killed cause they SUCK. This war actually partly caused ww2, with Hitler being embarrassed and hating the ponies that caused everyone to become bronies. Your grandpa fought in this war, just letting you know. Also, the only reason it was more violent than ww2 is because it was fought in the trenches and you can grab a club and pwn each other. You can read more detailed events about it here.
World War II[]
World War II consisted of the UnUnited Kingdom, Soviet Russia, the United States of UnAmerica, France, and China against Nazi Germany, Japan, and the Mushroom Kingdom. It took 2000 years for the war to fully diminish. You see, as a quick summary it was started by Hitler, who was angry that the bronies and jewish people wouldn't allow him to be a artist, and he SWORE revenge! He begun by mass genociding everyone who denied him as a artist, effectively murdering 99.9999% of the bronies and building a HUGE army of Nazis. Armed with Mario's Tanks, and some Panzers which were pretty gud, he really though he was a pro or something cause he took france with his soldiers which were under 9000. So he decided and invaded teh Soviet union. Though, that did come back to bite him in the butt because it was too cold and they were too whiny and sniffled and DIED and couldn't take the might of the motherland, so they losed and Hitler became a n00b which is why his clone took over. But then even that wasn't enough because all the countries started going full throttle and killing all of his Nazis and the clone died, so when his army was cooked hitler failed. After all that, the mushroom kingdom got messed up with their crappy tanks and Japan got nuked by Unamerica. You can read the full WW2 story here. But yeah, it didn't end happily ever after.
World War III[]
This war was at the end of the UnWorld. Having the title for the largest and longest war known, it is the BIGGEST WAR in the UnUniverse, unlike world war 4 which was fought with sticks and stones. I'll try to wrap up the all the little, big events in one little storybook. OF COURSE, Germany started the war again and got pissed they lost ww2 so Marguerite Williams, who took over as fuhrer decided to invade crap again. They really don't know when to stop do they? So yeah, they battled and stuff and war and killing unseen at a level not known before, like a war like ww2 but 9000x more killing with more morshu bombs than you can count due to hundreds of years of peace. But then, everyone realized Germany also lost 2 world wars and that they were a n00b, so everyone just began bullying germany with Bombs. But yeah, since everything was upgraded and had advanced technological improvements with Clorox bombs that bleach your skin, it had so much mayhem that I can't even fully give you the data on a list cause you'll get old and jump in the Pit of Retirement. After all the useless mutually assured destruction and the cheap temu nukes being used, germany LOST again. You can read more about it with info here.
World War IV[]
This war started in 99999999999999999999999999999999999999999999999AA and ended in 786587643854358437654385568537867657688676876768976587573475373687657658776876867AA. Longest war in the UnUniverse, but not very technological due to everything being destroyed. There isn't much info on on it because everything was written on rocks using Flinstone tactics and those were cracked after some time, ruining all the information. All that's known is it was just a bunch of monkeys throwing rocks at each other for a LONNNGGG time.
World War V - XXX[]
Nothing is known about these wars besides that they exist.
World War XXXI and above[]
We are not even sure these exist, but they probably last from infinity and beyond.