[2] The M3 was developed as a replacement for the World War I-era U.S. Mark I trench knife, primarily to conserve strategic metal resources.

Catalog of Standard Ordnance Items of 1943 clearly explained: The Trench Knife M3 has been developed to fill the need in modern warfare for hand-to-hand fighting.

[4] Reports of blade failures on M3s in service increased as soldiers began to use their trench knives for ordinary utility tasks such as opening ammunition crates and food ration tins, a role for which the M3 had not been designed.

[4] After the Ordnance Department began developing a proprietary bayonet for use on the M1 carbine, it was realized that the new carbine bayonet, which already incorporated the M3 blade design and leather-wrap grip, could also replace the M3 in service in a secondary role as a fighting knife.

The final M3 production run did not take place until August 1944, by which time 2,590,247 M3 trench knives had been produced.

The M3 was initially issued with a stitched and riveted leather M6 scabbard with a protective steel tip designed to prevent the point from piercing the sheath and injuring the wearer.

[5] U.S. paratroopers frequently wore an M3 and sheath tied to a boot for emergency use in cutting parachute lines or close-quarters defense.

[2][14][5] The M8 and the later M8A1 scabbards both have a resin-impregnated cotton canvas body, painted olive drab, with a steel throat.