Jackie Robinson served in the United States Army. He was drafted in 1942 and assigned to a segregated cavalry unit at Fort Riley, Kansas, during World War II.
Robinson's military career became an important part of his story because he challenged segregation before he ever played in the major leagues. Although he had the qualifications for Officer Candidate School, his application and those of other Black soldiers were delayed. Support from boxer Joe Louis and civilian aide Truman Gibson helped press the Army to admit them.
Robinson completed officer training and was commissioned as a second lieutenant in January 1943. In 1944, he faced a military court-martial after refusing to move to the back of an Army bus at Fort Hood, Texas. He was ultimately acquitted. The Marines, Air Force, and Navy are incorrect choices: Robinson's documented wartime service was in the Army.