This name for an American soldier is of unknown origin. Despite being popularly associated with the First World War, doughboy actually dates to the Mexican-American War in 1847. From a letter by Lieutenant N.J.T. Dana of 1 January 1847:
We were stopped about eight o’clock at the foot of a large, steep hill, where we “doughboys” had to wait for the artillery to get their carriages over.1
There is an older sense, however, that of a type of dumpling. This sense dates to the 17th century; from a text written by a pirate named Basil Ringrose in 1685 and published in the 18th century book The History of the Bucaniers of America:
These men that were landed, had each of them three or four cakes of bread (called by the English, Dough-boys) for their provision of victuals.2
Several conjectures about the origin have been advanced, but none have any real evidence to support them. One such conjecture is that the buttons on Civil War uniforms resembled the dumpling.
A second is that infantryman in the 1850s wore white belts and used flour to cover nicks and scratches. Again, the date is off, but is getting closer.
And a third is that it is from the dust-caked uniforms from marching through Mexico, the dough- being a variant of adobe.
1Napoleon Jackson Tecumseh Dana, Monterrey is Ours!: The Mexican War Letters of Lt. Dana, 1845-1847, edited by Robert H. Ferrell (Lexington: University Press of Kentucky, 1990), 166.
2Alexandre Olivier Exquemelin, Basil Ringrose, and et.al., The History of the Bucaniers of America, Fifth Edition (London, 1771), 237.
Copyright 1997-2015, by David Wilton