Justice League of America, Vol. 1

The teams who discovered some of Degaton's atomic missiles (see part 4 of Crisis On Earth Prime) report back to Earth-Two's President Roosevelt on their successes but there are still more missiles to find. One team, including Power Girl, travel to Switzerland where they encounter Degaton's minions and Johnny Quick of Earth-Three. During the fight, Degaton's soldiers launch the missiles, forcing the heroes to dispose of them quickly and safely. Another team visit Prof Zee - Degaton's employer and inventor of the time machine. They convince him to allow them to use the machine to travel forward in time to 1962 and across dimensions to Earth-Prime in order to prevent Degaton stealing the missiles in the first place. In 1942, the heroes discover Degaton's hideout and, after battling his soldiers and Owlman of Earth-Three, defeat him. On Earth-Prime, as the Crime Syndicate - under Degaton's orders - attempt to steal the missiles, they are prevented by the heroes. With that crime never having taken place, the rest of the adventure could not have happened and history rewrites itself with the Justice League, Justice Society and All Star Squadron having no recollection of it at all.