The World War II M3 Trench Knife

Posted by Devin H. on 9/5/2013 to Military History
M3 Trench KnifeIf there is one side arm easily recognized as a fighting icon from WWII, it is the US Army M3 Trench Knife. Initially manufactured to equip soldiers not armed with a bayonet, this sturdy and almost irreplaceable weapon endured through most of WWII until challenged and replace by later weapons and more functional designs.

Originally issued in 1943, this legendary trench knife soon became the standard government issue for those engaged in close hand-to-hand combat such as élite forces, principally the US Army Rangers.

Its Design

Although not a general dual-purpose utility knife as other famed Marine Corps issue, it always rose to the occasion on the battle field.

A Directive from the U.S. Catalog of Standard Ordnance Items of 1943 stated:

“The Trench Knife M3 has been developed to fill the need in modern warfare for hand-to-hand fighting. While designated for issue to soldiers not armed with the bayonet, it was especially designed for such shock units as parachute troops and Rangers.”

As a manufacturing rule, the M3 Trench knife came with a narrow 6.75-inch bayonet-style, spear-point blade; moreover, it also had a sharpened secondary 3.5-inch blade edge.

Production of its grooved leather handle became more simplified with later styling of the grip that formed a stack of polished, lacquered leather washers.

Originally issued with a leather M4 sheath, this particular combination formed a guard to protect its wearer from injury. Its distinctive rawhide thong enabled the soldier to tie the sheathed knife to his calf leg. Paratroopers from the American Army especially tied this effective combo of knife and sheath to their boots while cutting parachute lines or in close combat situations.


When first issued, the knife that was basically well constructed and balanced, met with some heated disapproval by paratroopers and Rangers alike. They found the tool quite handy when used as a throw weapon; however, they found greater utility when used for thrusting or stabbing maneuvers. As far as slashing, they generally reported that there were better weapons available to a combat soldier.

As the war progressed, the reports of blade failures in the field also increased. Many negative findings came from the fact that soldiers were commonly utilizing the M3s for utility tasks--to open ammo crates and food ration tins in the field.

Retirement From Active Duty

A do-over ensued when the M1 Carbine was re-designed to carry a knife-type bayonet with the M3 used as a pattern; hence evolved the US Army M4.

The M3, declared limited standard issue, terminated its valiant and formidable service as a soldier's stellar and trust-worthy companion in the field of combat. Its demise came in August, 1944 with its retirement from active duty.

Historically, the M3 trench knife served one of the shortest periods of service of any US combat knife. However, its bold blade design still formed part of weaponry in the form of the M4, M5, M6 and M7 bayonets.

Tidbit: To its credit, even the British SAS replaced their own legendary Fairbairn-Sykes Fighting Knife, Commando Dagger, with a better quality and more endurable M3. Eventually, the new M3 knife replacement for the British army saw active duty as a robust fighter in theaters of war in Italy and North West Europe. It also saw active duty during several Malaysian campaigns by British troops.