High Quality Content by WIKIPEDIA articles! PC Patrol Craft were a class of vessel of the United States Navy during World War II. During World War II, Germany?s U-boat campaign was strangling the United Kingdom by cutting off her supplies from the United States. After the attack on Pearl Harbor, the United States joined this Battle of the Atlantic. The United States Navy, desperate to halt the carnage, needed more antisubmarine ships. Destroyers took too long to build, so the Navy built PCs.