Vertical Envelopment: The Beginnings of the Heliborne Air Assault

In 1946, the US Military began considering the practical applications of helicopters.  The USMC formed its first experimental helicopter squadron, HMX-1, at the Marine Base at Quantico, Virginia in December 1947.  

It was intended that the use of helicopters to insert troops and supplies ahead of a Marine Expeditionary Force would minimise the risk of losing a large force if it were attacked while massing at a beachhead.  It was envisioned that Marine Corps heliborne troops could land inland and open up potential beachheads rapidly allowing landing forces to fan out as soon as they landed.  This tactic was termed ’Vertical Envelopment’ by the USMC.  Marine Corps Commandant General Alexander Vandegrift supported the concept summarising the concept:

“With a relatively unlimited choice of landing areas, troops can be landed in combat formations and under full control of the flanks or rear of a hostile position.  The helicopter’s speed makes transport dispersion at sea a matter of no disadvantage and introduces a time-space factor that will avoid presenting at any one time a remunerative atomic target.”

While the helicopter had been experimented with by a number of other US Military service branches it was the USMC which first began experimentation for combat operations.  HMX-1, commanded byColonel Edward C. Dyer,began training and experimentation with a variety of helicopters including Piasecki HRP-1s (see image #1), Sikorsky H-5s and later Sikorsky H-19 Chickasaws (see image #2). 1948 saw a number of field exercise incorporating the use of helicopters and the publishing of the first manual to look at deploying helicopters entitled: Amphibious Operations–Employment of Helicopters (Tentative)’. 

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Navy Sikorsky H-5 in action in Korea (source)

The limited lift capacities of the early helicopters, the Piasecki HRP-1 for example could carry only 6 men or 2,000 lbs of cargo, meant that the number of troops deployable was limited unless used in large numbers. However, the Sikorsky H-19 doubled this and was used extensively during the Korean War.

With the outbreak of the Korean War and the rushing of US troops to defend the Pusan Perimeter in August 1950, elements of HMX-1 squadron were dispatched to support US Marines fighting along the perimeter.   Four helicopters of HMX-1 were initially deployed as observer and medical evacuation aircraft as well as on various transport missions.  HMX-1 did not perform any ‘Vertical Envelopment’ operations during 1950-51 however, its role was seen as vital and the squadron was used as a cadre to train further helicopter crews.   These trainee crews went on to form Marine Helicopter Transport Squadron 161 (HMR-161)who saw extensive action during the Korean War.   

Between 1951 and 1953 the United Nations forces in Korea held a defensive line across the Korean Peninsular called the Jamestown Line. With the arrival of the fully trained and equipped HMR-161 in September 1951 preparations began for the USMC’s first Vertical Envelopment operation.  On the 13th September HMR-161 assisted a battalion-sized operation codenamed Operation Windmill I, flying 28 flights in just under three hours delivering 18,848 lbs of supplies and evacuating 74 seriously wounded troops.  Later the same month HMR-161 launched its first combat air insertion mission during Operation Summit landing a company of 224 Marines on Hill 884.  The operation began with the landing of a security element at the proposed landing zone followed by a two landing site preparation teams.   Twelve helicopters then began ferrying in troops, five at a time, and supplies taking just over four hours to complete the insertion. 

In October the most ambitious insertion yet was attempted during Operation Bumblebee with the twelve helicopters of HMR-161 transporting an entire battalion.  In just under 66 hours almost 1,000 men were airlifted 15 miles to Hill 702.  By the end of the war in July 1953, HMR-161 had transported 60,046 people and approximately  7,500,000 lbs of cargo.

HMX-1 and HMR-161 proved the concept of 'Vertical Envelopment’ during their operations in Korea.  The lessons learnt would be built upon by other militaries engaged in Algeria, Egypt, Africa and Vietnam.  The first combat helicopter assault was completed during Operation Musketeer by Royal Marines’ 45 Commando in November 1956 during the Suez Crisis.  

Today, the HMX-1 squadron is famous for providing the Marine One helicopter which is at the disposal of the US President and his cabinet.


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Whirlybirds: US. Marine Helicopters in Korea, R.J. Brown (2003)

The Marine Helicopter And The Korean War, R.R. Propst (1989) (source)

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This encirclement was the most horrifying moment of the whole battle in the latest episode of GoT. The writers mentioned where they got the idea from.

When the Carthaginian cavalry attacked the Romans in the rear and the African flanking echelons assailed them on their right and left, the advance of the Roman infantry was brought to an abrupt halt. The Romans were enclosed in a pocket with no means of escape. The Carthaginians created a wall and began destroying them. Polybius wrote, “as their outer ranks were continually cut down, and the survivors forced to pull back and huddle together, they were finally all killed where they stood.”

Feline Body Language

Cats communicate many complex concepts through body language. They lead many actions with a motion of their head: a head pushing forward is a greeting, a head held in an upright position expresses confidence and a lowered head expresses either aggression or submission, depending on the position of the ears and tail. In general, a cat will use every body part to communicate her emotions and intentions, so even though the head begins the communication, the communication does not end until the tip of the tail is involved.


Cats use scent to communicate, as well as body language. The scents they use are called “pheromones,” which are secreted by glands on their foreheads, lips, front paws, flanks, and rears. Because each cat produces its own “formula” of pheromone, cats can use pheromones to recognize each other. When a cat applies her own pheromones to an object or to another animal or person, she is using the scent to mark that object, animal or person as her own. When cats share their pheromones in a group, it might be a way of becoming at ease with each other or creating a pecking order.

Nose Touching

Cats touch each other’s noses to engage in a friendly greeting. They are also sniffing each other’s pheromones to identify each other. When cats touch noses, they are taking part in a behavior called “allorubbing,” which may be something like a handshake or a hug in human terms. Allorubbing is more common in feral cats than in housepets. Your cat uses a variation of this behavior, lip rubbing, to mark objects (rather than people or other animals) with her scent.

Head-Butting (Bunting)

Head-butting and allorubbing are pieces of the same puzzle. Head-butting, also called “bunting,” takes place between cats who know each other well. It is usually a mutual behavior: that is, the two cats will gently touch the crowns of their heads or their cheeks together in order to express affection. Head-butting often leads to full-body rubbing and to tail-twining. When your cat touches her nose to your face or head-butts you, she is showing her affection and bonding with you. Petting your kitty in response to allorubbing, head-butting, or body rubbing reinforces that bond and may be reassuring to your kitty.