Justice League of America, Vol. 1 #88 (1971)

The Last Survivors of Earth
Survivors of the ancient land of Mu who had taken to the stars, return to Earth to find it over-run with humans and plan to engineer natural disasters wherever relics of their civilisation are on the Earth.As the League attempt to avert the disasters as the occur, unknown to them three normal people who hold relics of Mu destroy them, thus stopping the disasters.While the League are unaware of why the problems are overcome, the Mu spacecraft is destroyed by one man - who had been abducted by it - throwing a wrench into the engines, thus saving the Earth.
Release Date: 1971