The 14-inch M1920 railway gun was the last model

railway gun A railway gun, also called a railroad gun, is a large artillery piece, often surplus naval artillery, mounted on, transported by, and fired from a specially designed railroad car, railway wagon. Many countries have built railway guns, but the ...

to be deployed by the

United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

. It was an upgrade of the US Navy

14"/50 caliber railway gun The 14"/50 caliber railway guns were spare US Navy Mk 4 14 inch/50 caliber guns mounted on railway cars and operated by US Navy crews in France in the closing months of World War I. Background In 1917 the Allies were losing an artillery duel again ...

. Only four were deployed; two in the Harbor Defenses of Los Angeles and two in the

Panama Canal Zone The Panama Canal Zone ( es, Zona del Canal de Panamá), also simply known as the Canal Zone, was an unincorporated territory of the United States, located in the Isthmus of Panama, that existed from 1903 to 1979. It was located within the terr ...

, where they could be shifted between the harbor defenses of Cristobal (Atlantic) or Balboa (Pacific).

History

After the close of

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, the

US Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cla ...

wanted to incorporate the lessons learned from other railway gun mounts and fulfill coastal artillery requirements for hitting a moving target. An effort to design a more universal mount for the Navy's Mk. IV 14"/50 caliber gun was undertaken. The primary difference from the earlier Navy versions lies in the M1920 carriage, which could be raised and lowered. Prepositioned fixed mounts were installed at the forts, and the gun's rail trucks could be taken out from under the frame. After the removal of the rail trucks, the gun was lowered and bolted onto a pivot point for rapid 360 degree movement, necessary for tracking ships in coast defense. The M1920 carriage made the gun much more flexible. It allowed for the standard practice of using a curved piece of rail to traverse the gun, and it enabled the gun to be used in a fixed position. Two guns were deployed to

Fort MacArthur Fort MacArthur is a former United States Army installation in San Pedro, Los Angeles, California (now the port community of Los Angeles). A small section remains in military use by the United States Air Force as a housing and administrative annex ...

in the Harbor Defenses of Los Angeles, with firing platforms at Fort MacArthur and Long Beach. The remaining two guns were deployed to

Fort Grant Fort Amador ( es, Fuerte Amador) and Fort Grant were former United States Army bases built to protect the Pacific (southern) end of the Panama Canal at Panama Bay. Amador was the primary on-land site, lying below the Bridge of the Americas. Grant ...

and Fort Randolph in the

. The two guns deployed to the Panama Canal Zone could be moved to either coast on the

Panama Canal Railway The Panama Canal Railway ( es, Ferrocarril de Panamá) is a railway line linking the Atlantic Ocean to the Pacific Ocean in Central America. The route stretches across the Isthmus of Panama from Colón (Atlantic) to Balboa (Pacific, near P ...

. After World War Two ended, the threat of a massive war was over and the United States scrapped these weapons as well.Military Railroads on the Panama Canal Zone by Charles S. Small, Railroad monographs 1982

Models

The Mk.IV gun was manufactured in two models: * M1920MI centerline of breechblock mechanism canted 16 degrees counterclockwise to fit recoil band * M1920MII breech mechanism is set straight in relation to axis of tube.

Sighting and fire control equipment

The following sighting equipment was used with the gun: * bore sight * firing tables- 14-m-1, 14-e-3, 14-g-2. * M1 fire adjustment board * M1 generating unit (mounted on the forward railway truck) * M1 gunners quadrant * M1 plotting and relocating board * M1 prediction scale * M1A1 height finder * M1A1 range correction board * M7 spotting board * M8 helium filling kit * M1910 azimuth instrument * M1912A1

clinometer An inclinometer or clinometer is an instrument used for measuring angles of slope, elevation, or depression of an object with respect to gravity's direction. It is also known as a ''tilt indicator'', ''tilt sensor'', ''tilt meter'', ''slope ...

* M1917MI panoramic telescope * M1918 aiming rule * M1922 panoramic telescope

Support cars

* M1 powder car * M1 projectile car * M2 fire control car * M1918 repair car

Fate

All four guns were cut up for scrap in 1946.

Gallery

File:14in-railway-gun-M1920-CAJ192211.jpg, A M1920 on the test range. File:Naval gun, 10-12-22 LCCN2016846776 (cropped).jpg, A M1920 on the test range. File:Naval gun, 10-12-22 LCCN2016846777 (cropped).jpg, A group photo with a M1920.

References

Bibliography

* * McGovern, Terrance and Smith, Bolling, ''American Coastal Defences 1885–1950'' (Fortress series, Book 44), Osprey Publishing 2006, * Military Railroads on the Panama Canal Zone by Charles S. Small, Railroad monographs 1982 *
Vol. I at this link
* TM 9-2300 Standard Artillery and Fire Control Material. dated 1944 * FM 4-35 Service of the Piece; 14-inch Gun, M1920MII on Railway Mount, M1920 (1940) * SNL E-9 * SNL E-33
Coast Artillery Journal December 1929
* American Coast Artillery Materiel 192

(extensive manufacturing information) * Coast Artillery Journal March April 1934

External links

"Gun Train Guards Ends of Panama Canal -- Rolling Fort Crosses Isthmus in Two Hours" ''Popular Mechanics'', December 1934 pp.844-845
excellent drawings in article
FortWiki gun type list
{{Authority control 356 mm artillery Artillery of the United States Coastal artillery Railway guns World War II artillery of the United States Military equipment introduced in the 1920s