While "the Yanks" were "over there" in WWI, the Salvation Army Donut Girls served the troops coffee and donuts. The donuts were a bit of a novelty to the American troops since it was primarily a European treat. When they came home from the war, they brought the donut with them. Here is the Salvation Army's recipe for the donut along with a video.
The origins of the doughnut are scattered, but it is thought that they first came to America from France in the 17th century. The earliest reference I have personally ever found for doughnuts was in Laura Ingalls Wilder's book, Farmer Boy, which recounts her husband, Almanzo's youth as a boy in Malone, New York. I've been to Almanzo's home which is near the Canadian border. The street signs were in both English and French! I remember reading about the French in the book. Well...guess what? Here is another recipe I found, that is apparently from Almanzo's mother complete with the tantalizing description from the book, Farmer Boy. Even though I haven't read this book in years, it's easy to see why I remember it so well.
While running across all this history on the doughnut, I decided to cook some for dinner tonight...except I didn't have time. It was quite the busy day so I swung by the nearest doughnut shop (at the grocery store) and we picked out some doughnuts to eat with our omelettes! Quite a fitting combination, perhaps, since our soldiers in WWI were mostly fighting in France.
Even though Almanzo enjoyed doughnuts in the mid-19th century, doughnuts did not become popular in the United States until after WWI when the veterans of the Great War pined for their yummy snacks!
Then in 1938, the Salvation Army declared National Doughnut Day in order to raise money for the military! Of course the Salvation Army Doughnut Girls renewed the tradition by serving doughnuts to the soldiers in WWII.