Final answer:
The US military began to de-segregate in 1948 with the issuing of Executive Order 9981 by President Truman, influenced by civil rights advocacy and the hypocrisy of segregated forces in a democracy.
Step-by-step explanation:
The US military began the process of de-segregating in 1948 when President Truman issued Executive Order 9981. This decision came about due to several factors including the advocacy of civil rights groups like the NAACP, the discrimination and underutilization of African American soldiers during World War II, and the contradictory nature of fighting for democracy abroad while maintaining segregated forces.
Moreover, Truman’s engagement with civil rights issues and the international focus on human rights within the United Nations context also played a role in prompting this significant change. By mandating equal treatment and opportunity in the armed forces regardless of race, ethnicity, religion, or national origin, Truman’s orders began the process of integrating the US military ahead of broader societal integration during the Civil Rights era.