The 3rd (Prince of Wales's) Dragoon Guards was a cavalry regiment in the British Army, first raised in 1685. It saw service for three centuries, before being amalgamated into the 3rd/6th Dragoon Guards in 1922. The regiment was first raised as the Earl of Plymouth's Regiment of Horse in 1685, by the regimenting of various independent troops, and ranked as the 4th Regiment of Horse. In 1746 it was ranked as the 3rd Dragoon Guards, and formally titled in 1751 as the 3rd Regiment of Dragoon Guards.