was organized on 1 December 1917 from existing Regular Army units and Connecticut National Guard companies from the Harbor Defenses of Long Island Sound.

[1] Reactivated on 2 June 1941 as the 56th Coast Artillery Regiment (155 mm gun) (Mobile) at Fort Cronkhite, California in the Harbor Defenses of San Francisco (see below).

The 506th Arty was organized at La Crosse, Wisconsin, in August 1922 and redesignated 506th CA (AA) Regt 20 February 1924.

The remaining elements of the 56th CA Regt in HDSF continued to man 155 mm guns at Ft. Cronkhite and Drakes Bay.

Orders were received mid-September 1942, to move 3rd Bn, 56th CA, (Btrys E & F with Btry D attached) to the Southern California Sector, WDC.

One detachment of HHB was assigned to 3rd Bn command post at Ventura, the other platoon to HD Los Angeles.

A Gold color metal and enamel device 1 3/16 inches (3.02 cm) in height overall consisting of a shield blazoned: Gules, four searchlight beams radiant from middle base Or; on a chief Sable a winged projectile of the second.

The distinctive unit insignia was originally approved for the 506th Coast Artillery (AA), Organized Reserves on 12 March 1929.

The crest commemorates the award of the Distinguished Unit Citation given the organization in World War II for Hurtgen Forest by the hurst of trees and the arrow.

The trident and Torii allude to the Presidential Unit Citation (Navy) awarded the organization for action in Inchon during the Korean War.

World War II Korea Vietnam This article incorporates public domain material from 56th Air Defense Artillery.