His son, John, was the first of the family to receive a university education, being educated at Exeter College, Oxford. His father became the friend of Robert Rich, 2nd Earl of Warwick and succeeded in arranging the marriage of his son to the Earl's younger daughter Lucy, thereby cementing an alliance which would bring John into contact with influential radical preachers of the time. Convinced of the more Calvinist doctrines of the Church of England, John became alarmed at the Arminian slant of King Charles I's religious policy and his increasingly autocratic rule; he believed the King had been misled by evil councillors. For this reason John Robartes fought on the side of the Parliament and, according to his view of things, also the King, during the Civil War. He fought with valour at the Battle of Edgehill 23 October 1642, and at the First Battle of Newbury, 20 September 1643.