3-inch guns; they were not replaced until 1946, when the battery became a saluting battery. In 1924 the Coast Artillery Corps' harbor defense garrisons transitioned from a company-based organization to a regimental organization. The Harbor Defenses of Chesapeake Bay (as renamed in 1925) were garrisoned by the 12th Coast Artillery Regiment of the regular army, with the 246th Coast Artillery Regiment as the Virginia National Guard component. In 1932 the 12th Coast Artillery was effectively redesignated as the 2nd Coast Artillery, continuing as the garrison of Chesapeake Bay. World War II During World War II, Fort Monroe continued as headquarters for the Harbor Defenses of Chesapeake Bay. However, during the war new gun batteries were built at Fort Story and at Fort John Custis on Cape Charles. These rendered Fort Monroe's heavy guns obsolete, and between 1942 and 1944 all of the fort's and guns and mortars were scrapped. However, the two rapid-fire guns of Battery Montgomery remained until 1948. A gun battery of two guns (Battery 124) was proposed for Fort Monroe but not built. A new Anti-Motor Torpedo Boat (AMTB) battery (AMTB 23) was built in 1943, with two fixed, dual-purpose (anti-surface and anti-aircraft) 90 mm guns at the old Battery Parrott, which was partly rebuilt to accommodate them. This type of battery was usually authorized two fixed and two mobile 90 mm guns and two 37 mm or 40 mm guns, but it is unclear where the additional weapons were located. In addition, submarine barriers and underwater mine fields continued to be controlled from Fort Monroe. But by the end of the Second World War, the vast array of armaments guarding the Chesapeake was made largely obsolete due to the development of the long-range bomber and the refinement of naval aviation. Essentially all of the United States' coast defense guns were scrapped by the end of 1948. Post World War II Since World War II, Fort Monroe has been a major Army training headquarters. However, in 1946 the Coast Artillery School relocated to Fort Winfield Scott in San Francisco, where it was disestablished in 1949; the remnant of the Coast Artillery Corps was also disestablished a year later. Also in 1946 Battery Irwin became a saluting battery with two 3-inch M1902 guns relocated from Fort Wool, which are still in place. The fort also hosted some Cold War antiaircraft defenses in the 1950s; a battery of four