 In 1643 Sir John was leading a regiment of 1,200 men in Devon, and was taken prisoner by royal forces after the surrender of Exeter in September 1643.Northcote was kept captive until the autumn of 1644, when he was exchanged, and resumed his Parliamentary seat in May 1645.He subscribed to the Covenant, and was excluded from Parliament in Pride's Purge in December 1648, but returned to the House of Commons once more as Member for Devon in all three Parliaments of the Protectorate.