The USS Isabel (SP-521), later designated PY-10, was a notable vessel with a complex service history spanning from World War I through World War II. Originally built as a private yacht in 1917 by Bath Iron Works in Bath, Maine, she was constructed for John North Willys, an automobile manufacturer from Toledo, Ohio. Willys designed her with qualities that made her suitable for naval acquisition, and following the U.S. entry into World War I, the Navy purchased her before she was completed. She was converted into a naval destroyer and commissioned at the Boston Navy Yard on 28 December 1917. During World War I, Isabel conducted convoy escort missions from France, where she demonstrated her combat capabilities, notably engaging German submarines. She participated in four submarine encounters and was credited with sinking a submarine on 18 March 1918, alongside USS Reid. Her commanding officer, Lieutenant Commander Shoemaker, received the Navy Cross for his service. After the war, Isabel served various auxiliary roles, including as a tender to the submarine USS K-5 on the Mississippi River and later supporting the NC-4 flying boats from Long Island. In 1920, her classification changed from a destroyer to a patrol yacht (PY-10), and she was decommissioned in April of that year. Recommissioned in 1921, Isabel was assigned to the Far East to join the Yangtze Patrol, becoming the flagship of Rear Admiral William H. G. Bullard. Based in Shanghai, she protected American interests during turbulent Chinese political events, including the Nanking Incident of 1927, often coming under fire herself. Throughout the 1930s and early 1940s, Isabel served with the Asiatic Fleet in the Philippines and China, excelling in gunnery and patrol duties. In December 1941, she was tasked with a secret reconnaissance mission along Japanese-occupied Indochina just before the attack on Pearl Harbor. During World War II, Isabel played a vital role escorting submarines and convoys in the East Indies, surviving air raids and engaging enemy submarines. She was among the last American ships to leave Java ahead of Japanese forces and later served as an escort and training vessel in Fremantle, Australia. Decommissioned in February 1946, she was struck from the Navy List and sold for scrap shortly thereafter. Her long and varied career highlights her importance as a multi-role vessel, from a private yacht to a combat and patrol ship across two World Wars, and her service in protecting American interests in Asia.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.