From the United States National Archives:
National Doughnut Day started in 1938 when it was created by the Salvation Army to honor the women who served doughnuts to the soldiers during World War I. Doughnuts were back on the front lines in World War II.
Elizabeth A. Richardson, the woman on the left in this photograph, is standing in front of her Clubmobile, a single-decker bus fitted with coffee and doughnut-making equipment that drove around the England, bringing cheer to the soldiers stationed there. “I consider myself fortunate to be in Clubmobile—can’t conceive of anything else,” she wrote to her parents in World War II.
But like many of the young men she served doughnuts to, Elizabeth did not return home. She was killed in plane crash in July 25, 1945, and is buried in the American Cemetery in Normandy. You can read more about her story in this Prologue magazine article: http://go.usa.gov/d4k