He was the son of Sir Henry Marten, LL.D., a loyal Judge of the Admiralty. After receiving a learned education at Oxford, he entered one of the Inns of Court, and travelled in France. Having a stake in Berkshire—for he inherited a property of £3000 a year, besides several thousand pounds in money—he was elected, 1640, one of the members for the county in the last two Parliaments of King Charles I. His chief seat was at Becket, in the parish of Shrivenham. He afterwards obtained a grant of £1000 a year to him and his heirs out of the forfeited estates of the Duke of Buckingham. His early marriage with a rich widow, selected by his father, but not affected by himself, also benefited his finances. From the commencement of the Civil Wars he was a violent Republican; and as early as 1643 openly expressed his opinion of the desirability of the destruction of the King and his children, for which rather premature advice he was expelled from the House of Commons, and underwent a short imprisonment in the Tower. He was appointed by the House of Commons a Colonel of Horse and Governor of Reading, but made less mark as a soldier than as a rapacious spoiler of the adherents of the King, which earned him the opprobrious nickname of “Plunder-master General”. Being empowered to dispose of the Regalia and royal trappings, he once invested GEORGE WITHER—who had been made one of Cromwell’s Major-Generals—with them, and so accoutred induced the old Poet to strut up and down Westminster Abbey to the scandal of right-thinking people. To him also were referred the alterations in the public arms, the Great Seal, and the legends upon the money. Upon the latter was a shield bearing the cross of St. George, encircled by a palm and olive branch, and inscribed _The Commonwealth of England_, and on the reverse, _God with us, 1648_; which occasioned the remark “that God and the Commonwealth were not on the same side”. Nothing apparently could damp the ill-timed jocosity too often prevalent in those troublous times, for at MARTEN’S trial, 16th October, 1660, Ewer, who had been his servant, swore that “at the signing of the warrant for the King’s execution he did see a pen in Mr. CROMWELL’S hand, and he marked Mr. MARTEN in the face with it, and Mr. MARTEN did the like to him”. But many of his excesses were condoned in the eyes of both his friends and enemies by his generous and humane spirit.