an important battle near York in 1644 during the English Civil War, which gave Cromwell control of the north of England. (July 2, 1644) First major Royalist defeat in the English Civil Wars. Royalist forces under Prince Rupert relieved the siege of York and pursued the Parliamentary forces to nearby Long Marston. A surprise counterattack by Parliamentary forces under Oliver Cromwell caused heavy losses to Royalist troops. With the fall of York, Charles I lost control of the north, and Cromwell emerged as the leading Parliamentary general