Armoured cavalry are combat units using armoured fighting vehicles (AFVs) instead of horses. They began to replace horse cavalry in the heavy shock and the light reconnaissance, skirmishing and exploitation/pursuit roles in most armies commencing after the First World War.

Armoured cavalry, or simply armoured units, may be primarily equipped with heavy tanks or lighter and faster light tanks, armoured cars, or even scout cars in the case of what is often known as cavalry scout.  Motorised or mechanised infantry may make up a portion of the unit in some countries, supported by either motorised or self-propelled artillery, with possibly airmobile troops on helicopters included.

Historical background

Horse-mounted troops used various forms of armour for their own protection, and often added protective elements to their mount's tack. Horse armour included hardened leather in the ancient world, expanding to barding and even plate armour by the Middle Ages. From antiquity, light cavalry was generally more agile and more lightly protected than heavy cavalry, which used larger horses needed to carry heavier, more reinforced equipment and riders.

Between the late 17th and mid-19th centuries, armoured cavalry referred to those cavalry regiments that retained the cuirass, and were commonly known as cuirassiers. After the First World War cavalry units were mostly converted from horses to either armoured cars or tanks which became known as either mechanized cavalry fulfilling a reconnaissance role, or armoured cavalry serving in the offensive role that seeks to break through the enemy defences.

In October 1928, a new era began for the cavalry of the British Army when the 11th Hussars became the first regular cavalry regiment to "mechanize", to change from a horsed cavalry role to a mechanized one, re-equipping with armoured cars previously used by the Royal Tank Corps. Other regiments followed suit; in April 1939, the Royal Armoured Corps was formed to encompass the eighteen mechanized cavalry regiments of the line alongside the eight battalions of the Royal Tank Regiment, but did not include the Household Cavalry. The remaining two regular cavalry regiments were based in Palestine, and following the outbreak of war retained their horses until 1940 (the Royal Dragoon Guards) and 1941 (the Royal Scots Greys). Following mechanization, the few remaining distinctions of unit type became meaningless; cavalry regiments moved between the heavy and light armoured roles regardless of their names.

Vietnam: U.S. armoured cavalry

U.S. Army armoured cavalry had the mission of reconnaissance and security.  Unlike armoured and infantry units, U.S. Cavalry is organized into squadrons and troops, which are equivalent to battalions and companies respectively.  A regiment of armoured cavalry, such as the 11th Armored Cavalry Regiment (the Black Horse Regiment) in Vietnam, consisted of three full squadrons of armoured cavalry. The squadron normally consisted of a headquarters troop, three cavalry troops, a tank company, a 155-mm self-propelled howitzer battery, and an aviation troop.  The three ground troops were a mixture of M48 Patton or M551 Sheridan tanks and M113 ACAVs (Armored Cavalry Assault Vehicles). The aviation troop of the squadron was equipped with helicopters, consisting of UH-1 transports, OH-6 Cayuse scouts, OH-58 Kiowa scout/gunships, and AH-1 Cobra gunships.

Armoured cavalry regiments operated in country for the Corps/Theater Commander, while the squadrons operated as the "eyes and ears" for the US Army Division Commanders. An Army brigade would only be authorized a cavalry troop, and not a whole cavalry squadron.

According to Army doctrine, the cavalry would find the enemy, and hold the enemy in place, until the heavy forces were brought up to deal with the located enemy. This process was known as the battle hand-off.  At this point the cavalry is free to disengage and continue with other missions. Security missions could be rear guard, flank guard, or advance guard – the same functions as performed by infantrymen, only with tanks and ACAVs.  With the infantry, the advance guard would be called the point man.

During the Vietnam War, it was the mission of armour (tanks) to close with the enemy and defeat them using firepower, manoeuvre, and shock action.  With the US Infantry, the mission was the same, minus the shock power.  Artillery's mission was to add firepower to the equation.  The US Armored Cavalry's mission was to find the enemy and/or provide security for the Army, while having the means to destroy the enemy if becoming decisively engaged.  In Vietnam, the US Army deployed 1 Armored Cavalry Regiment (containing 3 squadrons and an aviation squadron), 7 Armored Cavalry Squadrons, and 2 Armored Cavalry Troops:
 11th Armored Cavalry Regiment
 1st Squadron
 2nd Squadron
 3rd Squadron
 Regimental Aviation Squadron
 1st Squadron, 1st Cavalry Regiment
 2nd Squadron, 1st Cavalry Regiment
 1st Squadron, 4th Cavalry Regiment
 3rd Squadron, 4th Cavalry Regiment
 3rd Squadron, 5th Cavalry Regiment
 1st Squadron, 10th Cavalry Regiment
 2nd Squadron, 17th Cavalry Regiment
 Troop A, 4th Squadron, 12th Cavalry Regiment
 Troop B, 1st Squadron, 17th Cavalry Regiment

From about January 1969 until the last mounted unit re-deployed from Vietnam in 1972 (air units remained in country), most armoured cavalry units (except the 11th ACR's tank companies) were equipped with the M551 Sheridan armored airborne reconnaissance assault vehicle (today, known to historians as a light tank).

Other usage

Armoured cavalry units can use hunter-killer teams. Scout vehicles and tanks can operate in concert, suited respectively as "hunters" and "killers". For instance, in U.S. land forces, the cavalry scouts of a team (often mounted in M3 Bradley Cavalry Fighting Vehicles) go in search of enemy positions, and flush the enemy into a designated kill zone where the armored units can inflict more damage on the enemy than the "hunters" alone could hope to.

See also
 Armoured Cavalry Arm – main armoured force of France
 Air cavalry
 Armoured fist
 List of US Army armored cavalry regiments
Current British cavalry regiments in armoured role
The Royal Scots Dragoon Guards (Carabiniers and Greys)
The Royal Dragoon Guards
The Queen's Royal Hussars (The Queen's Own and Royal Irish)
The King's Royal Hussars
2nd Royal Tank Regiment

References
Starry, Donn A., General. "Mounted Combat In Vietnam." Vietnam Studies; Department of the Army. First printed 1978-CMH Pub 90-17.

Cavalry