History
Magneto declared war on all of humanity after years of watching Mutants get killed and was joined by Charles Xavier. They were initially winning the war, until S.H.I.E.L.D. kidnapped Reed Richards' family and used him to create a virus that wiped out the whole of mutantkind, killing Magneto and Charles. Reed was devastated by the genocide he had caused, so he and the Fantastic Four traveled to Mars to rebuild their lives.[1]