Field artillery has been called “The King of Battle.” And for good reason. Great generals throughout history have lauded the power and necessity of artillery in battle. Artillery wins battles and therefore could win wars. Mortars are basically the light artillery of the infantry. The U.S. military uses a variety of mortar calibers for infantry support. The 81mm mortar is a portable, mobile, medium mortar at the infantry’s disposal.

Mortars are indirect-fire weapon systems. The term “indirect fire” means firing at an enemy without having a direct line of sight. A rifle or a tank, for example, are direct-fire weapons. You see the enemy, you aim, and fire that munition directly at him. Mortars are indirect-fire weapons that rely on mathematical calculations to fire a munition at a high angle, which then arcs down onto the intended target.


The Infantry Mortar Platoon

US Infantry mortar platoon composition
Unit composition of the infantry mortar platoon taken from ATP 3-21.20. Unclassified.

In the U.S. Army and the U.S. Marine Corps, the 81mm mortar is a battalion asset. This means that each infantry battalion has a mortar platoon providing indirect fire support for the other infantry companies in the battalion. This mortar platoon has four squads of infantrymen, plus a fire direction section (squad), that makes the fire control calculations. Each mortar platoon has four 81mm medium mortars at its disposal — one for each squad. They also have four M120 heavy mortars, as well, but typically each squad only operates one mortar at a time.