From <
http://www.word-detective.com/011098.html#doughboy>
Dear Word Detective: A Social Studies teacher I know is trying to find out why American infantrymen in World War I came to be known as "doughboys." My dictionary also refers to the term "doughfoot" as having the same meaning. Did it have something to do with feet that were swollen like rising dough? -- Jan Lundeberg, via the Internet.
The human mind is a funny thing, especially, apparently, mine. I read your letter and, being a good American consumer, I immediately thought of cute little Pop'n Fresh (or however you spell his infernal name), "the Pillsbury Doughboy" of a thousand TV commercials. Sad, isn't it? You probably won't be surprised to learn that I used to own a cat named after a popular fabric softener.
There turns out to be quite a bit of controversy about the origin of "doughboy" as a slang term for a soldier or infantryman, but one certainty is that the term is much older than most people would suspect. Although it gained currency in popular use during World War I, "doughboy" first showed up in print in 1847, before the American Civil War. General George Armstrong Custer's widow mentioned the term in her memoirs written in 1887, explaining that "doughboys" were small doughnuts often served to sailors aboard ship. According to Mrs. Custer, the term was applied to infantrymen because the large brass buttons on their uniforms reminded someone of these naval "doughboys." Lending support to at least the culinary aspect of Mrs. Custer's theory is the fact that "doughboy" has meant "a boiled flour dumpling" to sailors since about 1685.
There are other theories about "doughboy," such as those tracing the term to the adobe clay barracks housing soldiers in the American Southwest at that time ("adobe boys" becoming "doughboys"), or soldiers using adobe dust to whiten their white uniform belts, or soldiers' boots being caked with adobe mud. None of these theories is impossible, but neither is any especially convincing.
If I had to pick a theory, I'd say that it's most likely that "doughboys" owed their moniker to those little doughnuts Mrs. Custer mentioned -- not because the soldiers wore buttons that resembled them, but because "doughboys" were a staple of the military diet at the time.
1847! Looks like the doughboys are older than they look!
Tom