The Mount Weather War is an important armed conflict between the Grounder/Sky People Alliance and the Mountain Men of Mount Weather. The war unofficially began at least fifty-six years before the start of series when the Mountain Men began to abduct Grounders to use their bodies to filter radiation. The war ended at the battle of Mount Weather on the 2nd of November 2149 with a Sky People victory and the almost total annihilation of the Mountain Men with Carl Emerson being the sole survivor.