In 1919, John T. Thompson invented the American classic Thompson submachine gun.  His invention gained its notoriety during the Prohibition era and picked up nicknames such as ‘Tommy Gun’, ‘Trench Broom’, ‘Chicago Piano’ and ‘The Chopper’.  It wasn’t until 1938 that the US military began officially using this submachine gun.  The Thompson quickly became a favorite among the soldier due in part to its reliability coupled with its .45 ACP and its high volume of automatic fire.  The Thomson submachine gun has become a favorite among collectors due to its historical significance.


History of Development

Gen. John T. Thompson’s vision began with a desire to develop a safely operated rifle with semi-automatic fire that could replace the current service rifles, which were bolt action.  In 1916 Thompson was able to secure finances (through Thomas Ryan) to begin the Auto-Ordnance company to develop his idea.  Thompson had three key developers on this project:  Theodore Eickhoff, Oscar Payne and George Goll.  With the information they had gathered throughout their work, the vision of a ‘hand-held machine gun’ using a .45 ACP developed – this project became known as ‘Annihilator I’.  Design flaws on the initial prototype were eventually corrected, but World War I had already come to an end before the first prototypes could be exported to Europe.


After the war, the weapon was renamed the ‘Thompson Submachine Gun’.  Though others were developing similar type weapons, Thompson’s gun was the first to actually be branded and promoted as a submachine gun.  The first production run (M1921) was marketed to civilians but few were purchased due to the high price tag.  A small number were sold to the US Postal Inspection Service as a means to protect mail carriers from the wave or current robberies).  Eventually, sales extended to the US Marine Corps, several US police departments and some international sales mainly Central and South America.


Thompson Is Put to the Test

The US Marine Corps first used their submachine guns in China during the Banana Wars.  The weapon proved effective to counter ambush attempts made by the Nicaraguan guerrillas.  The only downside noted to using the Thompson was the weapon’s actual weight, its inability to maintain accuracy beyond 50 yards and the .45 ACP pistol cartridge lacked penetrating power.


The guns were also used by the Irish Republican Army in 1921 during the final month of battle in the Irish War of Independence. They were also used from 1922-23 during the Irish Civil War.  The Irish did not find the Thompson submachine gun to be an effective weapon.  They noted only 32% of those attacked with the Thompson received serious injuries.


The Thompson submachine gun gained the most infamy in the United States during the days of prohibition where it found itself in the hands of gangsters and motorized bandits.  Lawmen pursuing these men also used the Thompson submachine gun.  Hollywood began using the guns as well – including their well-known St. Valentine’s Day Massacre.


US Military Adopts the Thompson Submachine Gun

The Thompson submachine gun was first adopted by the US military in 1938 and subsequently used throughout WWII.  Two military variants were issued:


M1928A1 which included:

  • Provisions for box and drum magazines
  • Cutts compensator
  • Cooling fins on the barrel
  • A delayed blowback action
  • Charging handle located on the top of its receiver


M1A1 which included:

  • Barrel w/o cooling fins
  • Simplified rear sight
  • Provision for box magazines only
  • Employed a straight blowback action
  • Charging handle located on the side of the receiver


The Thompson was used by the Allies during World War II.  It military use extends far beyond WWII though.  It was also used in the Arab-Israeli war, the Greek Civil War, the Korean War, the Cuban Revolution, the Vietnam War and the 1969-1998 Northern Ireland conflict.  Current variants of the Thompson submachine gun continue to be produced today, bringing it lifetime production total to well over 1,700,000.