Where did G. I. Joe come from?

I did a search of the archives and snopes and came up empty. Does anyone here know where the term “G. I. Joe” came from? I’m asking about the reference to the common soldier, not the toy.

WWII cartoonist Bill Mauldin’s “Willie and Joe” cartoons. If he didn’t actually invent it, he certainly popularized it.

G.I. stands for Government Issue. Everything a soldier received was G.I.
Joe was a generic term for a dude (Hey Joe whatja know?). Therefore G.I. Joe was a generic term for a dogface soldier.

I’m a little reluctant to give him 100% credit, too, but this site isn’t so hesitant:

And, of course, Loach is right about the “G.I.” part.

“G.I.” goes back to at least 1918.

The term “G.I. Joe” to mean the averge soldier is first cited in an Army book in 1936, but it was certainly popularized in 1942 by David Breger. Bill Mauldin’s cartoons came second, I believe, but certainly Mauldin is the one we remember today. But Breger’s stuff was produced in June of 1942.

Word Origins attributes it not to “government issue” nor “general infantry”, but to “galvanized iron” which acronym appeared in military supply documents as early as 1907: