Not just a simple war, a massive war. The whole world is plunge into chaos. I'd like the MC to be an expert when commanding troops, if possible has an important background(powerful clan, strong master,etc). Don't mention Night Ranger, The Grandmaster Strategist or The Human Emperor. Please!
Everlasting Immortal Firmament The World Online The war didn't involve the whole world though, only region
Pretty much every xianxia/xuanhuan/wuxia towards the end. Edit: Except for the Marquis of Grand Xia. Less than 100 chapters in and there was a full blown war.