Sad Sack was a comic created for Yank by a draftee in WWII. He was an animator for Disney who was drafted right off the picket line in 1941. There was no dialog in this strips. He can be seen as a precursor of Beetle Baley.
He not only ended up with his own comic, but with several spin-off comics.
I was mostly curious if he was now a forgotten character. I believe the answer is: Pretty much.