Royal Scots Dragoon Guards in the context of "Order of the Thistle"

The Royal Scots Greys was a cavalry regiment of the Scots Army that became a regiment of the British Army in 1707 upon the union of Scotland and England, continuing until 1971 when they amalgamated with the 3rd Carabiniers (Prince of Wales's Dragoon Guards) to form the Royal Scots Dragoon Guards. The regiment's history began in 1678, when three independent troops 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 by this stage and were already being referred to as the Grey Dragoons.

Following the formation of the united Kingdom of Great Britain in 1707, they were renamed The Royal North British Dragoons (North Britain then being the envisaged common name for Scotland), but were already being referred to as the Scots Greys. In 1713, they were renumbered the 2nd Dragoons as part of a deal between the commands of the English Army and the Scottish Army when the two were in the process of being unified into the British Army. They were also sometimes referred to, during the first Jacobite uprising, as Portmore's Dragoons. In 1877, their nickname was finally made official when they became the 2nd Dragoons (Royal Scots Greys), which was inverted in 1921 to The Royal Scots Greys (2nd Dragoons). They kept this title until 2 July 1971, when they amalgamated with the 3rd Carabiniers, forming the Royal Scots Dragoon Guards.

Edinburgh Castle (Scottish Gaelic: Caisteal Dhùn Èideann) is a historic castle in Edinburgh, Scotland. It stands on Castle Rock, which has been occupied by humans since at least the Iron Age. There has been a royal castle on the rock since the reign of Malcolm III in the 11th century, and the castle continued to be a royal residence until 1633. From the 15th century, the castle's residential role declined, and by the 17th century it was principally used as a military garrison. Its importance as a part of Scotland's national heritage was recognised increasingly from the early 19th century onwards, and various restoration programmes have been carried out over the past century and a half.

Edinburgh Castle has played a prominent role in Scottish history, and has served variously as a royal residence, an arsenal, a treasury, a national archive, a mint, a prison, a military fortress, and the home of the Honours of Scotland – the Scottish regalia. As one of the most important strongholds in the Kingdom of Scotland, the castle was involved in many historical conflicts from the Wars of Scottish Independence in the 14th century to the Jacobite rising of 1745. Research undertaken in 2014 identified 26 sieges in its 1,100-year history, giving it a claim to having been "the most besieged place in Great Britain and one of the most attacked in the world". Few of the present buildings pre-date the Lang Siege of 1573, when the medieval defences were largely destroyed by artillery bombardment. The most notable exceptions are St Margaret's Chapel from the early 12th century, which is regarded as the oldest building in Edinburgh, the Royal Palace, and the early 16th-century Great Hall. The castle is the site of the Scottish National War Memorial and the National War Museum. The British Army is still responsible for some parts of the castle, although its presence is now largely ceremonial and administrative. The castle is the regimental headquarters of the Royal Regiment of Scotland and the Royal Scots Dragoon Guards and houses their regimental museums, along with that of the Royal Scots.

A tank gun or tank cannon is the main armament of a tank. Modern tank guns are high-velocity, large-caliber artillery capable of firing kinetic energy penetrators, high-explosive anti-tank, and cannon-launched guided projectiles. Additional weapons, such as anti-aircraft guns, heavy machine guns and rocket launchers can also be mounted to tanks.

As the tank's primary armament, they are almost always employed in a direct fire mode to defeat a variety of ground targets at all ranges, including dug-in infantry, lightly armored vehicles, and especially other heavily armored tanks. They must provide accuracy, range, penetration, and rapid fire in a package that is as compact and lightweight as possible, to allow mounting in the cramped confines of an armored gun turret. Tank guns generally use self-contained ammunition, allowing rapid loading (or use of an autoloader). They often display a bulge in the barrel, which is a bore evacuator, or a device on the muzzle, which is a muzzle brake.

The 3rd Carabiniers (Prince of Wales's Dragoon Guards) was a cavalry regiment of the British Army. It was formed in 1922 as part of a reduction in the army's cavalry by the amalgamation of the 3rd Dragoon Guards (Prince of Wales's) and the Carabiniers (6th Dragoon Guards), to form the 3rd/6th Dragoon Guards. It was renamed the 3rd Carabiniers (Prince of Wales's Dragoon Guards) in 1928 and amalgamated with the Royal Scots Greys (2nd Dragoons), forming the Royal Scots Dragoon Guards (Carabiniers and Greys) in 1971.