Military service has long been associated with citizenship, and blacks have been part of every American war since the founding of this nation. Five thousand fought in the Revolutionary War, 180,000 fought in segregated units during the Civil War, and 380,000 enrolled in World War One. Although black participation increased with each major conflict, only 42,000 of the blacks in World War One belonged to combat units, a result of 20th century racial tensions that turned opinion against the use of black soldiers. Segregation persisted within the military establishment, including military aviation, through World War Two. Within a span of ten years, however, the Army Air Corps moved from having no African Americans among its ranks to become the United States Air Force, boasting tens of thousands of African Americans serving in many specialty areas. This dramatic change was inspired in part by the actions of the people who trained at Tuskegee Army Airfield or who served in the units of the Tuskegee experiment, collectively known as the Tuskegee Airmen. Their demonstrated skill in combat operations, their direct action protests against segregation outside of combat, and their remarkable commitment to preservation of military efficiency and discipline despite prejudices in semi-integrated settings combined to undermine the foundational justifications of military segregation, paving the way for Executive Order 9981 and integration of the Air Force