The 4th and 9th Regiments of Horse were raised in June 1685 during the rebellion against King James II led by his exiled nephew, James Scott the Duke of Monmouth. The 4th Regiment of Horse was composed of six troops from the English counties of Worcestershire, Oxfordshire, Northamptonshire, Bedfordshire, Huntingdonshire and Middlesex. Six troops were also raised in Hampshire, Nottinghamshire, Hertfordshire, Yorkshire, Suffolk and possibly Devon, to form the 9th or Queen Dowager’s Regiment of Horse. The latter regiment was armed with carbines (shortened muskets suitable for carrying on a saddle) which is the origin of its later title ‘The Carabiniers’.
Although the 4th Horse played no significant role in the campaign to suppress the Monmouth Rebellion, the 9th Horse took part in the final stages of the decisive battle at Sedgemoor. The Hampshire troop commanded by Lord Lumley also participated in the capture of Monmouth in July 1685.