Following demobilization after World War I, the 369th returned home and reverted to New York State service.  However, with war looming in Europe and Asia, in August 1940 the United States Congress authorized the induction of state National Guard units for federal service.  The Harlem Hellfighters were subsequently reorganized as the 369th Coast Artillery (Anti-Aircraft) in August 1940 and were inducted into Federal service on January 13, 1941.  Two days  later, the 369th was transported to Fort Ontario (Oswego, New York) for training, where their proficiency with 3” artillery guns earned them great respect and admiration.  After nine months they were relocated to Camp Edwards (Massachusetts) for additional training until the spring of 1942 before arriving in Hawaii later that June. 

            While on Hawaii, the 369th provided anti-aircraft defense for Marine Corps Air Station Ewa and other airfields on Oahu.  In 1943 the regiment was broken up and organized into the 369th Anti-Aircraft Artillery Gun Battalion and the 870th Anti-Aircraft Artillery Automatic Weapons Battalion.  In February 1945, as the threat of Japanese air attacks against Hawaii diminished, the 870th AAA began amphibious training at Camp Malaloke.  In April through June, the 870th participated in the Battle of Okinawa where in over 70 days of continuous combat, it captured more than 700 Japanese prisoners while successfully securing a strategic island stronghold in the Kerama Retto chain.