An Air Assault is a tactical or operational manoeuvre of an infantry unit airlifted by helicopters, usually to fulfil an aerial envelopment role in a larger ground operation plan. The role of the assaulting force is rarely to immediately engage and destroy enemy forces, but rather to seize and hold key terrain. In addition to regular infantry training, these units usually receive training in rappelling and air transportation, and their equipment is sometimes designed or field modified to allow better transportation in helicopters. Due to the transport load restrictions of helicopters, air assault forces are usually light infantry though light tracked armored fighting vehicles like the Russian BMD-1, German Wiesel 1 and Swedish Bv206 designed to fit the heavy lift helicopters which enable assaulting forces to combine air mobility with a degree of ground mechanisation. Invariably the assaulting troops are highly dependent on aerial fire support provided by escorting armed helicopters or fixed wing aircraft.
Air assault should not be confused with an airborne assault when infantry called paratroopers, and their weapons and supplies, are dropped by parachute from transport aircraft, often as part of a strategic offensive operation.
Another form of delivering troops to an area of combat operations by air which is not a type of air assault is called air landing, and can involve either glider infantry, before and during the Second World War, or almost any type of Combat Arms or Combat Support Arms troops using a secured airhead to form an airbridge for a larger airlift operation. An air landing airlift is also conducted as part of a strategic offensive operation.
Paratroopers were dropped by the Luftwaffe during the Battle of Crete, and by the Allies during Sicily, Normandy, and Holland operations. Meanwhile, the Germans were using helicopters such as the Focke Achgelis Fa 223 and Flettner Fl 265 to rescue shot down Luftwaffe pilots. The small batch of Flettner 265s were operated off ships in the Baltic Sea and were fitted with rescue winches. Fl 282s were used in many combat theatres, both land and sea and the large transport Fa 223s was even involved in rescues of civilians. The Fa 223 was used to airlift mountain infantry with 75mm guns and all their ammunition in the Alps close to Innsbruck.
Airborne tactics in WWII differed between nationalities and theaters of war. In Europe, Allied airborne tactics often involved broad area landings in advance of ground forces, with limited reinforcement. The airborne forces then linked up with the ground forces when they arrived.
The Luftwaffe tactic in Holland and Crete was to establish an airhead at an airfield using parachute and glider infantry similar to a beachhead in amphibious operations and rapidly reinforce the airhead with specially trained troops, such as the 22.Luftlandeinfanteriedivision, in military transport aircraft. In the Pacific Theatre, Allied forces performed a similar airborne landings of the 7th Division at Nadzab, west of Lae, between 7-9 and 12 September, with American paratroopers of the 503rd Parachute Infantry Regiment taking the airhead and the Australian 7th Division providing the reinforcing infantry in conventional transports. This operation follows the model of an air landing operation of today.
Units like the 1st Air Commando Group performed extensive aerial resupply using gliders and conventional transports in the China-Burma-India theater (CBI). The Germans fielded the first troop carrying helicopter, the FA-223 in WW2 and would have used it to rescue Italian dictator Mussolini after the glider assault had their aircraft not needed repairs at the time. In its stead, a short take-off and landing (STOL) Fieseler Storch observation plane was used to fly him to safety. The United States Army Air Forces flew Sikorsky R-4 helicopters in the China Burma India Theater, performing the first allied helicopter casualty evacuation. The helicopter on that mission could only carry one person other than the pilot. They also used the R-6 which could carry two casualties in pods on the side of the helicopter. All Allied helicopter pilots in WWII were trained by the United States Coast Guard at Brooklyn Air Station.
In 1946 U.S. Marine General Roy S. Geiger observed the atomic bomb tests at Bikini Atoll and instantly recognized that atomic bombs could render amphibious landings difficult because of the dense concentrations of troops, ships and material at the beachhead. The Commandant of the Marine Corps convened a special board, the Hogaboom Board, that recommended that the USMC develop transport helicopters in order to allow a more diffused attack on enemy shores. It also recommended that the USMC form an experimental helicopter squadron and HMX-1 was commissioned in 1947 with Sikorsky HO3S-1s. In 1948 the Marine Corps Schools came out with Amphibious Operations—Employment of Helicopters (Tentative), or Phib-31, which was the first manual for helicopter airmobile operations. The Marines used the term vertical envelopment instead of air mobility or air assault. HMX-1 performed its first vertical envelopment from the deck of an aircraft carrier in an exercise in 1949.
After the start of the Korean War, four HMX-1 helicopters were attached to VMO-6 and sent to the Pusan Perimeter in 1950. They were used for battlefield observation and control as well as medical evacuation and the rescue of fliers. During the Battle of Chosin Reservoir they were used for liaison between the different Marine units strung along the western edge of the Chosin Reservoir. The Marines began commissioning transport helicopter squadrons flying Sikorsky HRS-1s in 1951. After moving to Korea, these units began performing aerial resupply and aerial assault missions. HMR-161 transported over 200 Marines and 18,000 pounds of cargo in the first helicopter air assault in history in Operation Summit in September 1951. The first battalion-sized helicopter air assault was that of the 3rd Battalion 7th Marines in October 1951 in Operation Bumblebee.
General James Gavin, the famous U.S. Army airborne officer wrote "Cavalry, and I Don't Mean Horses" in Harper's, April 1954. This article was influential in getting the U.S. Army to start considering airmobile-type operations, but the Army was held back by the U.S. Air Force, which thought that it should control all aircraft including helicopters that would be used to support the Army.
Helicopter use in Indochina and North Africa, by the French Army was limited in the 1950s by the limited availability and capability of the helicopters of the time. Most application was in medical evacuation. However the utility of the helicopter was obvious to forward looking military planners.
An early attempt to apply air mobility to warfare was the Battle of Dien Bien Phu in 1954. French military leaders believed that they could resupply the garrison there by air indefinitely, regardless of the failure of these operations by the Luftwaffe on the Eastern Front. However, the air technology available, the means in which it was applied, and the terrain and geography led to failure and surrender of French troops.
The French Army subsequently gained considerable valuable experience during the Algerian War between 1954 and 1962. The French used American helicopters for what was termed "Aeromobilité". The first air assault operations were small, but quickly grew in size and scope to full battalion sized actions. French Army Light Aviation (Aviation Legère Armee de Terre, ALAT) helicopters were used as flying command posts, equipped with radios and to carry troops directly into battle. Helicopters were also used to supply units in the field and outposts.
On November 5, 1956 the Royal Marines' 45 Commando performed the first combat helicopter assault during an amphibious landing as part of Operation Musketeer, in Suez, Egypt. They were flown in Westland Whirlwind Mark 2s of 845 Naval Air Squadron from the deck of the HMS Theseus, and Whirlwinds and Bristol Sycamore HC.12s and HC.14s of the Joint Experimental Helicopter Unit (JEHU) of the RAF from the deck of HMS Ocean.
In 1956 the U.S. Navy modified and recommissioned the USS Thetis Bay, a WWII escort carrier, as an Assault Helicopter Aircraft Carrier (CVHA-1). It was the first ship purposely modified for air assault operations. The Marines started receiving their much-used Sikorsky HUS helicopters in 1957. They would be redesignated as UH-34s in 1962. Later three WWII Essex-class fleet carriers were also converted and in 1961 the U.S. Navy commissioned the USS Iwo Jima, the first carrier planned and built as a platform for air assault operations.
U.S. Army CH-21 helicopter transports arrived in Vietnam on 11 December 1961. Air assault operations using South Vietnamese (ARVN) troops began 12 days later in Operation Chopper. These were very successful at first but the Viet Cong (VC) began developing counter helicopter techniques and at Ap Bac on January 1963, 13 of 15 helicopters were hit and four shot down. The Army began adding machine guns and rockets to their smaller UH-1 Huey helicopters and developed the first purpose built gunship, the UH-1B with the M-6E3 armament system.
U.S. Marine helicopter squadrons began four month rotations through Vietnam as part of Operation SHUFLY on 15 April 1962. Six days later, they performed the first helicopter assault using U.S. Marine helicopters and ARVN troops. After April 1963 as losses began to mount, U.S. Army UH-1 Huey gunships escorted the Marine transports. The VC again used effective counter landing techniques and in Operation Sure Wind 202 on 27 April 1964, 17 of 21 helicopters were hit and three shot down.
The 2nd Battalion 3rd Marines made a night helicopter assault in the Elephant Valley south of Da Nang on 12 August 1965 shortly after Marine ground troops arrived in country. On 17 August 1965 in Operation Starlite the 2nd Battalion 4th Marines landed in three helicopter landing zones (LZs) west of the 1st VC Regiment in the Van Tuong village complex, south of Chu Lai, while the 3rd Battalion 3rd Marines landed on the beaches to the east. The transport helicopters were 24 UH-34s from HMM-361 and HMM-261 escorted by Marine and Army Hueys. VC losses were 614 killed, Marine losses were 45 KIA and 203 WIA.
The need for a new type of unit became apparent to the Tactical Mobility Requirements Board (normally referred to as the Howze Board) of the U.S. Army in 1962 when they saw a new kind of war heading their way. The Army saw that Vietnam was varied in terrain, having jungles, mountains, and rivers, making ground movement very difficult. To circumvent this problem, they developed the idea to use helicopters to move troops in and out and around a battlefield area, carry out the wounded, and drop off supplies.
Initially a new experimental unit was formed at Fort Benning, Georgia, the 11th Air Assault Division on 11 February 1963, combining light infantry with integral helicopter transport and air support. Following training and testing, the unit's assets were merged with the co-located 2nd Infantry Division and reflagged as the 1st Cavalry Division (Airmobile), continuing the tradition of the 1st Cavalry Division. Within several months it was sent to Viet Nam.
The first unit of the new division to see action was the 1st Battalion/U.S. 7th Cavalry Regiment, led by Lieutenant Colonel Harold G. Moore, an old army paratrooper. The 7th Cavalry was the same regiment that Custer had commanded at the ill fated Battle of the Little Bighorn. On November 14, 1965, he led his troops in the first large unit engagement of the 1960s Vietnam War, which took place near the Chu Pong massif near the Vietnam-Cambodia border. It is known today as the Battle of Ia Drang Valley.
This unit gave common currency to the U.S. term Air Cavalry. Units of this type may also be referred to as Airmobile or with other terms that describe the integration of air and ground combat forces within a single unit.
In the United States military, the air assault mission is now the primary role of the 101st Airborne Division (Air Assault). This unit is the Army's only division-sized helicopter-borne fighting force. Many of its soldiers are graduates of the Air Assault course qualifying them to insert and extract using fast rope and rappel means from a hover in addition to the ordinary walk on and off from an airlanded helicopter. Since the 101st relinquished its parachute capability in 1968, the 82nd Airborne Division is the United States Army's remaining parachute division.
All U.S. Marine Corps ground units are trained in basic air assault tactics and capable of performing heliborne operations that require them to walk off the airlanded helicopter.
There are other major "conventional" units in the United States Army that have parachute capabilities; the separate 173rd Airborne Brigade Combat Team, based in Italy and Germany, and the Alaska-based 4th Brigade Combat Team, 25th Infantry Division, which has its division headquarters in Hawaii, and the 1st Battalion (Airborne), 509th Infantry Regiment based in Fort Polk, Louisiana supporting the Joint Readiness Training Center as the opposing force for training rotational units. The 173rd ABCT parachuted into Northern Iraq during the invasion of Iraq in 2003. These units are considered regional quick reaction parachute forces for the Pacific and Atlantic regions.
The 16th Air Assault Brigade of the British Army is a unit that is tasked with performing air assaults. It contains paratroopers from the Parachute Regiment and infantry units trained in being inserted by helicopter, as well as light tanks and artillery.