The Royalists had intended to send the king's nephew and foremost field commander, Prince Rupert, to the northwest to retrieve the situation early in 1644. Rupert set up headquarters in Shrewsbury, from where he led a force to the Relief of Newark. It became even more important to regain the northwest when the Fairfaxes and a Scottish Covenanter army began the Siege of York on 22 April. As Rupert lacked the strength to proceed immediately to relieve York, it was agreed at a council of war in Oxford, the King's wartime capital, that he would first move into Lancashire to restore Royalist fortunes, use the Earl of Derby's influence to gather fresh recruits, and secure the port of Liverpool to allow communications with Royalist forces in Ireland.