Dated June 17, 1942 was the first issue of Yank, The Army Newspaper.
That issue contained a number of cartoons and comic strips by soldiers.
One of those comic strips was the first appearance of The Sad Sack by Sgt. George Baker.
The Sad Sack would be in Yank from the first to the last.
In the December 28, 1945 issue our hero got an honorable discharge and rejoins civilian life:
Some of those 1942 – 1945 Yank issues are available at the Internet Archive.
Five months later, on May 5, 1946 we get another view of those first post-Army days when
The Sad Sack becomes a syndicated Sunday page distributed to civilian newspapers.
Back to that first issue of Yank…
It also saw the debut of G. I. Joe by Corp. Dave Breger:
But the character had first appeared as Private Breger nearly a year earlier
as a panel in the August 30, 1941 issue of The Saturday Evening Post.
There were limits to patriotism. The Saturday Evening Post didn’t want to share
the “Private Breger” title and so soldier-cartoonist Breger coined the term “G. I. Joe.”
Yank featured some good cartoonists, including Sgt. Al Jaffee and Pfc. Bill Keane, as well as front-line illustrations that make it worth following that link and reading through a few issues.
But fergoodnessake don’t tell anyone what Sgt. Baker’s character was a Sad Sack of.