[quote=Asura]
I may need the details on that, seeing as how it would effect ol' princey boy, since his father ruled during it/he might've been alive during it.
[/quote]

Honestly, I was going to leave it as vague as possible. All I decided was that Lantus won Ylisse the war by performing a shitton of war crimes. Basically, his most infamous act is poisoning the water supply of Castle Plegia and the city around it to weaken the garrison and take the city with minimal casualties on his own side. Plenty of dead civilians from poisoned water, though.