Chalk (military)

In military terminology, a chalk is a group of paratroopers or other soldiers that deploy from a single aircraft. A chalk often corresponds to a platoon-sized unit for air assault operations, or a company-minus-sized organization for airborne operations. For air transport operations, it can consist of up to a company-plus-sized unit. Oftentimes, a load of paratroopers in one aircraft, prepared for a drop, is also referred to as a stick.

The term was first coined in World War II for airborne troops during Operation Overlord, the Allied invasion of Europe. The aircraft flight number was placed on the troops' backs with chalk. It was later used during the Vietnam War, when it was common practice to number with chalk the sides of the helicopters involved in an operation. During the Battle of Mogadishu (1993), the battle plan called for four chalks from the 75th Ranger Regiment to fast rope down from hovering MH-60L Black Hawk helicopters around the target building. The rangers would then create a four-corner defensive perimeter. The plan failed as two of the Black Hawks were shot down, and the assault turned into a forced evacuation.

Current military terminology a "chalk" may mean either passengers or equipment loaded as cargo. Equipment is loaded in the order it will be needed on arrival. It is not uncommon for planners to refer to aircraft loads by their chalk number, "You are in chalk 5 but your gear will be shipped in chalk 2."