Churchill began his career as page to the Duke of York, who became aware of his martial ambitions and obtained for him a pair of colours in the guards. After service in Tangier he became the lover of the Duchess of Cleveland, from whom he extracted £4,500. In 1671 he fought duels with Sir John Fenwick and Henry Herbert, and in the third Dutch war served under Turenne with great distinction. In 1678 he accompanied Sidney Godolphin I as military adviser on a mission to William of Orange. At the general election in the following year he was returned with Sir John Holmes for Newtown on the government interest, and marked ‘base’ on Shaftesbury’s list. But he went into exile in Flanders with the Duke of York before the first Exclusion Parliament met, and was given leave on 1 May 1679 to go into the country ‘for this whole session, in order to the recovery of his health’. Nevertheless Roger Morrice listed him as voting against the exclusion bill.
Churchill acquired one moiety of the Jennings estate by marriage, and bought the other in 1684. He thus enjoyed the principal interest at St. Albans, and in 1685 the mayor announced his candidature for the borough. In the event, however, his brother George was elected, perhaps because James II had made known his intention to give him an English peerage. He was by far the most important of the army deserters who went over to William of Orange in November 1688. The rest of his career, which has made him perhaps the most celebrated soldier in English history, is well-known. He died on 16 June 1722 and was buried in Westminster Abbey.2Som. Arch. and Nat. Hist. Soc. Proc. xxx, pt. 2, p. 44; HMC Verulam, 100-1.