The 4th Troop of Horse Guards was the Scottish unit within the Horse Guards Regiment. It was part of the United Kingdom military establishment from 1709 to 1746, but before the Union of the Parliaments, it had been an independent unit in Scotland, sometimes referred to in modern works as the Scots Troop of Horse. The unit's establishment is usually dated to 1661, although its antecedents extend back to the fifteenth century.