First appearance: G.I. Combat #138 (October - November 1969)
In the story, the crew of the Haunted Tank encounters the four members of what would become the group known as The Losers while rolling along. All four of the initial members of The Losers had previously been featured in other DC war comic books in the past.
Their own feature started running in Our Fighting Forces #123
(January-February 1970) and ran until issue #181 (September-October 1978).
And during 1974-1975, Jack Kirby was in charge of the series!
from Who's Who: The Definitive Directory of the DC Universe Vol. XIII (March 1986)