155 mm Long Tom

The 155 mm Gun M1 and M2 (later M59), widely known as Long Tom, were 155 millimeter calibre field guns used by the United States armed forces during World War II and Korean War. The Long Tom replaced the Canon de 155 mm GPF in United States service.

Development

Before entering World War I, the United States was poorly equipped with heavy artillery. To address this problem a number of foreign heavy artillery guns were adopted, including the Canon de 155 mm GPF. After the end of the war development work began in the United States on a design to improve upon the existing models of heavy gun and carriage. A number of prototypes were produced in the 1920s and 1930s, but the projects were put on hold due to lack of funds. In 1938 the 155 mm Gun T4 on Carriage T2 was finally adopted as 155 mm gun M1 on Carriage M1.

The new design used a barrel broadly similar to the earlier 155 mm GPF, but with an Asbury breech. The new split-trail carriage featured four roadwheels, each mounting two tires. The wheels could be lifted, allowing the gun to rest on a firing platform. This made the gun very stable and thus accurate.

The gun was developed into M1A1 and M2 variants. After World War II, the United States Army re-organized, and the gun was redesignated as the M59.

Service

The Long Tom saw combat for the first time in North African Campaign on December 24, 1942, with "A" Battery of the 36th Field Artillery Battalion. Eventually it equipped about 49 battalions, including 40 in the European Theater and 7 in the Pacific. The preferable prime mover was initially the Mack NO 6x6 7½ ton truck; from 1943 on it was replaced by the tracked M4 High Speed Tractor.^[1]

A small number of Long Tom guns were supplied via lend lease channels, to the United Kingdom (184) and France (25).^[2]

Variants

Gun variants:

• M1920 – prototype.
• T4 – prototype.
• M1 (1938) – first production variant, 20 built.
• M1A1 (1941) – modified breech ring.
  • M1A1E1 – prototype with chromium plated bore.
  • M1A1E3 – prototype with liquid cooling.
• M2 (1945) – modified breech ring.

Carriage variants:

• T2 – prototype.
• M1 (1938).
• M1A1 – refurbished T2 carriages.

The gun was also mounted on a modified M4 medium tank chassis, in mount M13. The resulting vehicle was initially designated 155 mm Gun Motor Carriage T83 and eventually standardized as 155 mm Gun Motor Carriage M40.^[3]

155 mm Gun Motor Carriage T79, based on T23 Medium Tank chassis, never advanced past proposal stage.^[4]

Ammunition

The gun utilized separate loading, bagged charge ammunition. The propelling charge consisted of base (9.23 kg) and increment (4.69 kg). The data in the table below is for supercharge (base and increment).

Existing examples

• US Army Ordnance Museum
• Timber Linn Park, Albany, Oregon

Aerial Photo on Google Maps

• VFW Zachary Taylor Post 3784, Baton Rouge, Louisiana.

Pendennis Castle, Cornwall, UK

See also

• List of U.S. Army weapons by supply catalog designation SNL D-24

Notes

1. ^ Zaloga – US Field Artillery of World War II, p 20-22.
2. ^ Zaloga – US Field Artillery of World War II, p 37.
3. ^ ^{a b c d} Hunnicutt – Sherman: A History of the American Medium Tank, p 353-355, 570.
4. ^ Hunnicutt – Pershing, A History of the Medium Tank T20 Series, p 158.
5. ^ Technical Manual TM 9-1901, Ammunition, p 197-202.
6. ^ Technical Manual TM 9-1904, Ammunition Inspection Guide, p 490-518.

References

• Bishop, Chris. Encyclopedia of Weapons of World War II. ISBN 0-7607-1022-8. 
• Hunnicutt, R. P. (1994). Sherman: A History of the American Medium Tank. Presidio Press. ISBN 0-89141-080-5. 
• Hunnicutt, R. P. (1996). Pershing, A History of the Medium Tank T20 Series. Feist Publications. ISBN 1-112-95450-3. 
• Zaloga, Steven J. (2007). US Field Artillery of World War II. New Vanguard 131. illustrated by Brian Delf. Osprey Publishing. ISBN 978-1-84603-061-1. 
• Technical Manual TM 9-1901, Artillery Ammunition. War Department, 1944. 
• Technical Manual TM 9-1904, Ammunition Inspection Guide. War Department, 1944. 

External links

• 155-mm. Novel Mechanical Features Give Big-Gun Power, Small Gun Speed, November 1942, Popular Science early article with many photos and detailed drawings showing how it is brought into firing position from travel mode.