Consequently, Wentworth followed suit and on 5 February 1644, he succeeded Sir Thomas Byron as colonel of the Prince of Wales's Regiment of Horse. At the Battle of Cropredy Bridge (June 1644) he commanded a cavalry brigade. He was afterward appointed major-general of horse in succession to Lord Wilmot, when the latter was dismissed before the battle of Lostwithiel. However, on 14 November 1644, he relinquished this post in order to join Lord Goring's army in the west country.