[1] The 242nd Coast Artillery was organized 29 May 1924 as the Connecticut National Guard component of the Harbor Defenses of Long Island Sound (HD Long Island Sound), New York.

In October 1944 the regiment was broken up into two battalions as part of an Army-wide reorganization.

By 1907 they had merged and were redesignated as the Coast Artillery Corps, Connecticut National Guard.

Following the American entry into World War I in April 1917, the companies were called into federal service by 25 July and redesignated as companies of the Coast Defenses of Long Island Sound.

[1] On 16 September 1940 the regiment was inducted into federal service in Bridgeport, Connecticut and moved to Fort H.G.