Justice League of America #71

Justice League of America #71 (On Sale: March 13, 1969) has a cover by Mike Sekowsky and George Roussos.

"...and So My World Ends" is by Denny O'Neil, Dick Dillin and Sid Greene. Diana Prince and her mentor Ching need help fighting an unknown man attacking a circus performance, so Diana calls the Justice League for help. Batman and Green Arrow respond and are able to defeat the man, only to find that he is fellow JLA member, J'onn J'onzz, the Martian Manhunter.

The Manhunter regains his senses and is taken to Justice League headquarters where he retells how he had recently returned to Mars only to find the planet threatened by Benn Blanx, a rebel who wished Mars to return to its warlike ways. Blanx had taken over the entire planet and was controlling a blue flame that threatens to destroy everyone on Mars. The Manhunter showed his people how to build a rocket to escape from Mars, then transported back to Earth to find more help. Somehow, along the way, his mind snapped and his sanity did not return till the JLA defeated him. J'onn asks the Justice League to help him save the surviving people of Mars.

The League agrees and, while headings for Mars to stop Blanx, are struck by a beam from a Martian weapon. The beam traps them in orbit around the Earth, but Green Arrow frees Superman who defeats the alien weapon. Nearing the planet Mars, they come across one of Blanx's ships and split up, Flash, Atom, Batman, Green Arrow, Hawkman and Martian Manhunter stay to attack the ship, while Green Lantern and Superman go to douse the blue flames.

Trapped by another ray, Atom and Flash free themselves and board the alien ship. They attack the renegade Martians and free their comrades from the ray. They make short work of the rest of the Martians on board.

On Mars, Superman tears off the surface of Mars afire in blue fire, and hurls it into space. Mars is dead.  Superman and Green Lantern watch the last survivors of Mars blasting off in the rocket that J'onn J'onzz built for them.

The Manhunter tracks down Blanx in the ruins of Mars and the two battle, the Manhunter eventually sending Blanx falling to his death. J'onn decides to go with the surviving Martians into space in search of a new home and says good-bye to the Justice League. Reprinted in Justice League of America Archives Vol. 9 HC.

Edited by Julius Schwartz.