Final answer:
The contributions of Black soldiers during World War II led to President Truman's 1948 ban on segregation in the U.S. Army.
Step-by-step explanation:
A primary factor that led to President Truman's 1948 ban on segregation in the U.S. Army was the contributions of Black soldiers during World War II. African American soldiers played a significant role in the war effort, demonstrating their bravery and dedication. Their contributions challenged prevailing racial prejudices and highlighted the need for equality in the military.
Learn more about Black soldiers' contributions in the U.S. Army during World War II