First appearance of Starman.
First appearance of Ultraman.
First appearance of Crime Syndicate.
On Earth-One, the Justice League of America has never been defeated in it's ceaseless was against crime and injustice ...On Earth-Two, the Justice Society of America has tasted only victory as it battles against the forces of evil ...Now meet the super-powered beings of Earth-Three -- triumphant in every one of their mission...When the super-beings of Earth-Three brazenly attack the Justice League -- to be followed up by an attack on the Justice Society -- it marks the beginning of a spectacular interdimensional struggle that shakes the very structure of three world!