A Stereotypical Poilu
You can't read much on the Great War without coming across this term at some point. It was a term of affection.
I just learned that Poilu means hairy, which makes sense if you ever look at photos from World War I. There are far more French soldiers with prominent facial hair than can be found among their allies.
A Poilu in the trenches early in the war
The term Poilu began to be used during the Napoleonic Era when the Grand Armée was largely drawn from the massive pool of unshaved farmers.
French Soldier After Battle
Poilus had the image of being long-suffering and brave, but also grumblers (this lead to the less flattering, but also common term, "Grognard") and prone to disobey unreasonable orders on pragmatic grounds.
A Poilu at Rest
The clean-shaven American doughboys were instead known for their youthful optimism and their cheerful naïveté.