The Brave and The Bold is a comic noteable for being a base for DC to introduce characters without investing heavily in book titles of their own. If the characters took off, get them a book. If not, keep them as secondary characters or just let them pass on into comic book oblivion. The Brave and The Bold eventually became a Batman book full of team-ups with other DC characters and then finally just a Batman book by itself.
Issue #29 isn't the first occurrence of the Justice League. It's not even the first occurrence of the league in the B and B. But what it does is solidfy the fact that the Justice League would work together from now on. The Brave and the Bold was a place for DC to try out things with their characters and with a second issue, that shows the editors were very happy with the outcome of the first.
Writers - Gardner Fox
Pencilers - Mike Sekowsky
Inkers - Bernard Sachs and Joe Giella
Editors - Julius Schwartz