Who was the first woman to officially serve in the U.S. Armed Forces?

The first woman to officially serve in the U.S. Armed Forces was Opha Mae Johnson, who enlisted in the Marine Corps Reserve on August 13, 1918, during World War I. Her enlistment marked a significant moment as she became one of the first women to serve in a structured military role, paving the way for future generations of women in the armed services. Johnson's service was part of a broader effort to integrate women into military roles, particularly as the U.S. faced personnel shortages during the war.

In contrast, Harriet Tubman, while a prominent figure in the abolitionist movement and noted for her contributions to the Civil War as a nurse and spy, did not serve in an official military capacity. Clara Barton, although a founder of the American Red Cross and instrumental in providing medical care during war, was also not recognized as an official member of the military. Betsy Ross is famous for her association with the creation of the American flag but had no military servic; her contributions occurred in a different historical context. Therefore, Opha Mae Johnson holds the distinction of being the first woman to serve officially in the U.S. Armed Forces, making her the correct answer to this question.