In 1944, segregated African-American Navy units were assigned dangerous loading operations. Most of these men were not trained in munitions handling, and safety standards were apparently often overlooked under heavy pressure to complete loading schedules.

In July 1944, a massive explosion occurred during the loading of two adjacent cargo ships at the U.S. Naval magazine at Port Chicago, California. 320 sailors and civilians were killed and 390 injured. Nearly two-thirds of the people killed at Port Chicago were African-American enlisted men.

A month later, when 258 African-American sailors refused to carry out loading orders under conditions they deemed unsafe,  208 received bad conduct discharges and pay forfeiture. The remaining 50 men were court-martialed and sentenced to 8-15 years of hard labor. In 1946, all were granted clemency.