USN:
Submarine chaser USS PC-1264 with her crew manning the rails. She was the only US Navy warship during WWII whose enlisted complement was entirely African-American.
At the time of the United States' entry into WWII, African-American crewmembers were only permitted to serve as messmen due to the Navy's fears that integrated crews would negatively affect the efficacy and discipline of the warships, despite integration being successfully done as far back as the Civil War. However, continued pressure from the NAACP and subsequent requests from President Roosevelt led to the Navy to allow African-Americans to enlist into general service starting June 1942 and plan two warships to have predominantly black crews, destroyer escort
USS Mason and submarine chaser
USS PC-1264.
Both ships retained an all-white officer complement throughout their wartime careers and originally their crews had a number of white petty officers aboard in order to train the sailors until their COs deemed them sufficient to take over, however
USS Mason retained those petty officers for the entirety of her career while
USS PC-1264 transferred them off after several months, making her the only one of the two to have a fully African-American crew. After her decommissioning in February 1946 she would be commanded by Ensign Samuel L. Gravely Jr, who would be in charge of her until she was put out of service; he would be the first African-American to serve aboard a US Navy warship as an officer, the first to command a warship, the first fleet commander, and the first flag officer.
While she and her crew did face a significant amount of prejudice at several points in her career, the officers onboard seemed to have treated them fairly and on one occasion the white crew of another submarine chaser defended her crew from a group of civilians intending to attack the ship, and both her and
USS Mason's performances and conduct were very highly regarded within the Navy and played a considerable role in the reevaluation of its discriminatory policies postwar. Though it should be noted one of
Mason's meritorious actions was not properly acknowledged and awarded until half a century later in 1994.