Charles Churchill joined the English Army as an ensign in the 3rd Regiment of Foot in 1674 and later received the colonelcy of that unit. He fought in numerous wars and battles, including Sedgemoor during Monmouth's Rebellion. He served under his brother when he captured Cork from its Jacobite Irish Army garrison in 1690. He then served on the continent at the Steenkerque and Landen. Churchill was promoted to brigadier-general in 1690 and to major-general in 1694.