U.S. Army paratroopers with the 82nd Airborne Division parachute from a C-130 Hercules aircraft during Operation Toy Drop 2007 at Pope Air Force Base
Paratroopers jump out of airplanes and use parachutes to land safely on the ground. This is one of the three types of "forced entry" strategic techniques for entering a theater of war; the other two being by land and by water. Their tactical advantage of entering the battlefield from the air is that they can attack areas not directly accessible by other transport. The ability of air assault to enter the battlefield from any location allows paratroopers to evade emplaced fortifications that guard from attack from a specific direction. The possible use of paratroopers also forces defenders to spread out to protect other areas which would otherwise be safe. Another common use for paratroopers is to establish an airhead for landing other units, as at the Battle of Crete.
This doctrine was first practically applied to warfare by the Italians and the Soviets. The first operational military parachute jump was logged in the night of August 9/10 1918 by Italian assault troops, when Lt. Alessandro Tandura dropped behind Austro-Hungarian lines near Vittorio Veneto on a reconnaissance and sabotage mission, followed on later nights by Lts. Ferruccio Nicoloso and Pier Arrigo Barnaba.
The first extensive use of paratroopers (Fallschirmjäger) was by the Germans during World War II. Later in the conflict paratroopers were used extensively by the Allied Forces. Cargo aircraft of the period (for example the German Ju 52 and the American C-47) being small, they rarely, if ever, jumped in groups much larger than 20 from one aircraft. In English, this load of paratroopers is called a "stick", while any load of soldiers gathered for air movement is known as a "chalk". The terms come from the common use of white chalk on the sides of aircraft and vehicles to mark and update numbers of personnel and equipment being emplaned.
In World War II, paratroopers most often used parachutes of a circular design. These parachutes could be steered to a small degree by pulling on the risers (four straps connecting the paratrooper's harness to the connectors) and suspension lines which attach to the parachute canopy itself. German paratroopers, whose harnesses had only a single riser attached at the back, could not manipulate their parachutes in such a manner. Today, paratroopers still use round parachutes, or round parachutes modified so as to be more fully controlled with toggles. The parachutes are usually deployed by a static line. Mobility of the parachutes is often deliberately limited to prevent scattering of the troops when a large number parachute together.
Some military exhibition units and special forces units use "ram-air" parachutes, which offer a high degree of maneuverability and are deployed manually (without a static line) from the desired altitude. Some use High-altitude military parachuting, also deploying manually.