Rupert, accompanied by the Earl of Derby, marched north from Shrewsbury on 16 May. He added Byron's army from Cheshire and North Wales to his own small force, giving him a total of 2,000 cavalry and 6,000 infantry. To cross the Mersey he had to secure a crossing at either Warrington or Stockport. He chose the latter, and stormed it on 25 May. The town was not fortified, and after a brief contest outside the town in the late evening the defenders fled to Manchester.