The 3rd (Prince of Wales's) Dragoon Guards was a cavalry regiment in the British Army, first raised in 1685 as the Earl of Plymouth's Regiment of Horse. It was renamed as the 3rd Regiment of Dragoon Guards in 1751 and the 3rd (Prince of Wales's) Dragoon Guards in 1765. It saw service for two centuries, including the First World War, before being amalgamated into the 3rd/6th Dragoon Guards in 1922.