Sir William Brockman (1595–1654) was an English landowner and military leader. He is best known for his staunch, if unsuccessful, defence of Maidstone in the Royalist cause, during the English Civil War.
William Brockman was born in England in 1595, at Lyminge in Kent, the son of Henry Brockman and Helen (Sawkins). He was educated at Oxford University and married an heiress: Anne (Bunce), the only daughter of Simon Bunce, Esq., of Lynsted. The couple had four daughters and two sons, the elder of whom died in infancy. In 1632, William Brockman, Esq., was knighted by King Charles I.
On the outbreak of the Civil War, the recently-knighted Sir William Brockman remained loyal to King Charles I and the Royalist cause. In 1642, Sir William was appointed High Sheriff of Kent by the King, but almost immediately he was arrested and imprisoned in Winchester Palace in Southwark, in London. The action seemed to have been a tactic to remove potentially influential Royalist supporters from the scene, and Brockman was replaced as Sheriff by Sir John Honeywood. William remained in custody until August 1645, although from June 1644 he transferred back to Kent, on the grounds that his health was deteriorating in the squalid London prison, to the fortified manor house known as Westenhanger Castle, only a couple of miles from his home at Beachborough.
In 1648, when the second period of conflict flared up, Sir William became directly involved in the fighting for the first and only time, under the command of Sir John Mayney. Separated from the main loyalist forces, the detachment in Maidstone had to fight unsupported against a large force of the New Model Army, under Sir Thomas Fairfax, or Lord Fairfax of Cameron as he had just become, having inherited the family peerage from the Kingdom of Scotland.