Airborne forces are military units, usually light infantry, set up to be moved by aircraft and ‘dropped’ into battle. Thus they can be placed behind enemy lines, and have an ability to deploy almost anywhere with little warning. The formations are limited only by the number and size of their aircraft, so given enough capacity a huge force can appear “out of nowhere” in minutes, an action referred to as vertical envelopment.

Conversely, airborne forces typically lack the supplies and equipment for prolonged combat operations, and are therefore more suited for airhead operations than long-term occupation; furthermore, parachute operations are particularly sensitive to adverse weather conditions. Advances in helicopter technology since World War II have brought increased flexibility to the scope of airborne operations, and helicopters have largely replaced large-scale parachute operations, and (almost) completely replaced combat glider operations. However, due to the limited range of helicopters and the limited number of troops that can be transported by them many countries retain Paratroopers as a valuable strategic asset.

General information
Airborne forces can be divided into three categories:

* Paratroopers — landed by parachute from aircraft,
* Airlanding troops — landed by aircraft (usually glider),
* Air assault troops or airmobile infantry — transported to the battle by helicopter or by aircraft.

The basic premise of the Airborne is that they can arrive with such speed that a coherent defence cannot be mounted against them for some time. It is assumed that this tactical advantage cannot be sustained for very long, so effective Airborne missions require the rapid advance of ground based troops in support.

Airborne forces are generally composed of infantry and light, non-armored vehicles and guns. After the Korean war, vehicles light enough to be dropped by parachute were developed, including the US M113 and retired M551 Sheridan airborne tank. The Soviets developed the BMD-1 and BMD-3 fighting vehicles. Helicopters can also transport vehicles such as the German Wiesel AWC, LAV-25 and British CVR(T) series. The Stryker was specified to be air-capable, but is too large to be practical to be transported by C-130 Hercules, helicopter, or air dropped. Large transports can carry only small numbers of main battle tanks or heavier infantry fighting vehicles.

Early history
The idea of “Sky Soldiers” is by no means a recent thought; Benjamin Franklin envisioned a time when soldiers would be delivered from the sky, with a crude, rudimentary understanding of parachutes. The first modern consideration of the use of what we now call a paratroop force dates back to 1918. Towards the end of World War I, Brigadier General Billy Mitchell suggested dropping elements of the United States 1st Infantry Division behind German lines near Metz. The war ended before such an attack could be seriously planned. Mitchell conceived that US troops could be rapidly trained to utilise parachutes and drop from converted bombers and land near Metz.

The first true paratroop drop was carried out by Italy in November 1927. Within a few years several battalions had been raised and were eventually formed into the two elite Folgore and Nembo divisions. Although these would later fight with distinction in World War II, the divisions were never used in a parachute drop. Men drawn from the Italian parachute forces were dropped in a special forces operation in North Africa in 1943 in an attempt to destroy the aircraft of the USAAF based there while they are still on the ground.

At about the same time the Soviet Union was also experimenting with the idea, planning to eventually drop entire units complete with vehicles including light tanks. To train enough experienced jumpers, parachute clubs were set up all over Russia with the aim of being able to transfer skilled members (or at least the men) into the armed forces if needed. Planning and organization progressed to the point that Corps-size drops were demonstrated to foreign observers, including the British Military Attache Archibald Wavell, in the Kiev military district maneuvers of 1935. By the late 1930s, the USSR possessed the largest Airborne forces in the world, but development stagnated prior to WW2 as a result of the Great Purge[citation needed].

One of the observing parties, Germany, was particularly interested. In 1936, Major F W Immans was ordered to set up a parachute school at Stendal (Borstel), and was allocated a number of Junkers Ju 52 aircraft to train on. The military had already purchased large numbers of Junkers Ju 52 aircraft which were now modified (slightly) for use as paratroop transports in addition to their other duties. The first training class was known as “Ausbildungskommando Immans”, They commenced the first course on May 3rd, 1936.

Other nations, including Japan, France and Poland also organized airborne units around this time.