page_title: Harbor Defenses of Boston
section_title: Interwar
hierarchical_section_title: Harbor Defenses of Boston / History / Interwar
caption_attribution_description: English: 16-inch gun M1919 at Fort Duvall, Hog Island, Hull, Massachusetts
context_page_description: The Harbor Defenses of Boston was a United States Army Coast Artillery Corps harbor defense command. It coordinated the coast defenses of Boston, Massachusetts from 1895 to 1950, beginning with the Endicott program. These included both coast artillery forts and underwater minefields. The command originated circa 1895 as the Boston Artillery District, was renamed Coast Defenses of Boston in 1913, and again renamed Harbor Defenses of Boston in 1925.
context_section_description: In 1920 a number of weapons deployed in limited quantities, plus the 3-inch gun M1898, were declared obsolete and removed from the forts. These included all Army 5-inch guns, the 4.72-inch Armstrong guns, the pair of 4-inch guns at Fort Warren, and many of the 3-inch guns throughout CD Boston, leading to some redeployments of 3-inch weapons.
  On 1 July 1924 the harbor defense garrisons completed the transition from a company-based organization to a regimental one, and on 9 June 1925 the commands were renamed from "Coast Defenses..." to "Harbor Defenses...". The 9th Coast Artillery was the Regular Army component of HD Boston from 1 July 1924 through 23 February 1944, when it was disbanded. The 241st Coast Artillery was the Massachusetts National Guard component of HD Boston from 30 April 1924 through inactivation on 7 October 1944.
  A major change in Boston Harbor between the wars required a new fort: the opening of a new ship channel in the northern part of the harbor. To cover this approach Fort Ruckman was built in Nahant from 1918 to 1924, with two 12-inch (305 mm) guns on M1917 long-range barbette carriages that increased the guns' range from 18,400 yards (16,800 m) to 29,300 yards (26,800 m). This type of weapon was developed in response to the progressive improvement of dreadnought battleships with better guns and armor. Although the end of World War I meant a general drawdown in US coast defenses, the Boston area was also chosen for one of the first 16-inch (406 mm) gun batteries built by the United States. This was Fort Duvall on Hog Island (now Spinnaker Island), south of the Hull peninsula and thus not visible from the ship channel, built 1919-1927. The fort had two M1919 16-inch (406 mm) guns on a new high-angle barbette carriage that allowed an elevation of 65 degrees and a range of 49,100 yards (44,900 m). This increased the opportunity for plunging fire against the decks of enemy warships as they approached. An alternate proposal in 1920 was to build a naval-type turret with two 16-inch guns on Great Brewster Island, but this was not implemented. Calf Island Military Reservation was also considered, but the battery was finally built (without a turret) as Fort Duvall.
caption: One of Fort Duvall's 16-inch M1919 guns.
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