The military mission of the small subchaser USS PC 1264 was to help protect American east coast naval convoys from U-boat attacks; although it performed routinely well, the 178-foot ship with a crew of 67 saw only minimal enemy action during its 22 months service (1944-46) and the only thing it sunk was probably a whale. Yet the activities of the PC 1264 -- related here by its captain, Purdon -- had a significant effect on U.S. Naval thinking, not about military but rather racial matters: the ship, as an experiment, carried an all-black crew of enlisted men (officers were white -- heretofore blacks had been excluded from the Navy, except as mess boys). PC 1264 proved of course that blacks are as good sailors as anyone else, dispelling the old myths of laziness, inherent ignorance, high VD rates, and routing ""the shibboleths of racial inferiority."" Purdon, who has written several other books (the latest, Mixed Company, 1970), tells the story in stiff third-person prose; it rarely comes alive although there are the obligatory Mr. Roberts touches (raids on the pantry; the ship's wayward mascot, Gismo the dog) and the repeated episodes of racial bigotry experienced by the crew during liberties provide a graphic backdrop to the ship's progress.