The Royal Scots Greys was a cavalry regiment

Cavalry regiments of the British Army

There are currently nine regular cavalry regiments of the British Army, with two tank regiments provided by the Royal Tank Regiment, traditionally classed alongside the cavalry, for a total of eleven regiments. Of these, five serve as armoured regiments, and five as formation reconnaissance...

 of the British Army

British Army

The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...

 from 1707 until 1971, when they amalgamated with the 3rd Carabiniers (Prince of Wales's Dragoon Guards)

3rd Carabiniers (Prince of Wales's Dragoon Guards)

The 3rd Carabiniers was a cavalry regiment of the British Army.-History:The regiment was formed in 1922 as part of a reduction in the army's cavalry by the amalgamation of the 3rd Dragoon Guards and The Carabiniers , to form the 3rd/6th Dragoon Guards...

 to form The Royal Scots Dragoon Guards (Carabiniers and Greys)

Royal Scots Dragoon Guards

The Royal Scots Dragoon Guards is a cavalry regiment of the British Army, and the senior Scottish regiment. It was formed on 2 July 1971 at Holyrood, Edinburgh, by the amalgamation of the 3rd Carabiniers The Royal Scots Dragoon Guards (Carabiniers and Greys) (SCOTS DG) is a cavalry regiment of...

.

The regiment

Regiment

A regiment is a major tactical military unit, composed of variable numbers of batteries, squadrons or battalions, commanded by a colonel or lieutenant colonel...

's history began in 1678, when three independent troop

Troop

A troop is a military unit, originally a small force of cavalry, subordinate to a squadron and headed by the troop leader. In many armies a troop is the equivalent unit to the infantry section or platoon...

s of Scots Dragoons were raised. In 1681 these troops were regimented to form The Royal Regiment of Scots Dragoons, numbered the 4th Dragoons in 1694. They were already mounted on grey horses

Gray (horse)

Gray or grey is a coat color of horses characterized by progressive silvering of the colored hairs of the coat. Most gray horses have black skin and dark eyes; unlike many depigmentation genes, gray does not affect skin or eye color Their adult hair coat is white, dappled, or white intermingled...

 by this stage and were already being referred to as the Grey Dragoons.