After their first appearances in The Brave and The Bold #28–30 in 1960, DC realized that the Justice League of America was a hit. It seemed that if heroes such as Batman, Superman, Flash, Hawkman, Wonder Woman, Green Lantern, and Aquaman were great on their own, they’d be even better together. Thus The Justice League of America was started, gathering these and other heroes together to fight the sort of foes that only their combined might could challenge.
Without the Justice League there would be no reason for Marvel to create the Avengers
We have added some more issues to Justice League of America collection
In our Ebay Store