Anti-Aircraft Weapons 1918-1930 1935 US Army Signal Corps

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“Historical Film No. 1132, Signal Corps, U.S. Army: Anti-Aircraft Weapons and Auxiliary Eqiupment.” Silent.

Public domain film from the Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied.

The 3-inch M1918 gun was a United States 3-inch anti-aircraft gun that entered service in 1918 and served until it was finally superseded by the 3″ M3 gun in 1930. The M3 was subsequently replaced by the M1 90mm AA gun just prior to the opening of World War II. The M3 3″ gun was later adapted for the anti-tank role, serving as the main armament of the M10 tank destroyer during World War II…

The predecessor : 3-inch M1917

The 3-inch M1917 was the US Army’s first dedicated anti-aircraft gun, entering service during World War I. Only a few were built, as the similar 3-inch M1918 on a mobile mount was considered more useful and was produced in large numbers.

Development of the M1917 started in 1915, and as the name implies, took two years to enter service. The gun was essentially an unmodified 3-inch M1903 (76.2 mm L/55) coastal-defense gun on a new mount allowing it to be aimed to high elevations. A number were used during the war. In the immediate post-war era it was developed as the 3-inch M1, using a removable barrel liner. In 1928 it was further improved in the 3-inch M3 by using a thicker removable liner that eased manufacturing.

History of the 3-inch M1918

For mobile use the original coastal gun was too heavy, so a smaller version was developed as the 3-inch M1918. For this role the barrel was cut down in length, to 50 calibers from 55, and a new breech was introduced to fire smaller rounds (76.2x585R, 212 cubic inches instead of 76.2x690R, 293 cubic inches). Like the adaptation that created the M2, the M1918 was also fitted with a removable liner in 1928, becoming the 3-inch M3. Another upgrade was started in 1931 as the T8, and then T9, but these projects were cancelled in 1938 when the 90 mm gun was selected in their place.

In September 1940 a project started to adapt the 3-inch gun to the anti-tank role, starting with the T9 experimental model but equipping it with the breech, recoil system and carriage borrowed from the 105mm M2 howitzer. The gun was accepted for service as the 3-inch M5.

A similar derivative of the T9 – the 3-inch M6 – was intended to be mounted on the M5 self-propelled gun, which was eventually abandoned. A final adaptation was the 3-inch M7, which included minor modifications for mounting on the M10 Wolverine. M7 saw wide use although it was supplanted to some extent by more powerful weapons such as the 90mm M3 and the British QF 17 pounder. 6,824 M7 guns were manufactured…

The only known surviving example is located at the Fort Sill museum.

Air defence is defined by NATO as “all measures designed to nullify or reduce the effectiveness of hostile air action.” They include ground-and air-based weapon systems, associated sensor systems, command and control arrangements and passive measures (e.g. barrage balloons). It may be used to protect naval, ground, and air forces in any location. However, for most countries the main effort has tended to be ‘homeland defence’. NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence as are initiatives to adapt air defence to the task of intercepting any projectile in flight.

In some countries, such as Britain and Germany during the Second World War, the Soviet Union and NATO’s Allied Command Europe, ground based air defence and air defence aircraft have been under integrated command and control. However, while overall air defence may be for homeland defence including military facilities, forces in the field, wherever they are, invariably deploy their own air defence capability if there is an air threat. A surface-based air defence capability can also be deployed offensively to deny the use of airspace to an opponent.

Until the 1950s, guns firing ballistic munitions ranging from 20 mm to 150 mm were the standard weapon; guided missiles then became dominant, except at the very shortest ranges…