The War for No Man's Land/Gunsmoke

The War for Gunsmoke is the unofficial title given to the climactic war fought between Vash the Stampede, his allies, and Federal Forces against Millions Knives and the Eye of Michael.

Pre-war Events
For at least two years before the onset of the war and almost a century and a half before hand, Millions Knives, brother of Vash the Stampede, sought a way to exterminate the human population of Gunsmoke as punishment for their exploitation of plants as a means of survival as well as cause his brother suffering for refusing to take his side. To do so Knives was known to have exterminated the citizens of many towns, including Carcasses and Tonim Town, as well as hired a group of assassins known as the Gung-ho Guns whom Vash would have to fight in the months leading up to and during the war.

Outbreak of War
The war is thought to have officially began with the Battle of Delnashville. Knives assaulted the city of Delnashville and the Federal Forces of the 31st Regiment located there with the Ark and several members of the Eye of Michael. The battle resulted in the near complete destruction of the city's population, civilian and otherwise, and the first loss the human race would experience in a series of battles as Knives advanced, absorbing plants as he went. Over the course of seven months, Knives would go on to steal plants and destroy almost every city within Gunsmoke's Southern Hemisphere.

The War for Gunsmoke ended Star Date: July 21st 0114 when Vash defeated Knives in a one-on-one duel and the humans of Gunsmoke and Earth convinced the plants who had fused with Knives that they wanted to live in peace together.