For the present the services of the new army were required solely in the field. On April 20 Cromwell, who was permitted to retain his commission forty days after the ordinance had passed, and whose allotted term had not yet expired, was sent with his cavalry to sweep round the King's head-quarters at Oxford in order to break up his arrangements for sending out the artillery needed by Rupert if he was again to take the field. Cromwell's movement was completely successful. He not only scattered a Royalist force at Islip, and captured Blechington House by sheer bluff, but he swept up all the draught horses on which Charles had counted for the removal of the guns, and thus incapacitated the enemy from immediate action. Rupert had to wait patiently for some time before he could leave his quarters. It is seldom that men realise at first the necessary consequences of an important change, and, on this occasion, the Committee of Both Kingdoms and the Parliament itself were slow to discover that, if the new army was to achieve victory, its movements must be guided, not by politicians at Westminster, but by the general in the field. The first act of the Committee was to send Fairfax with eleven thousand men to the relief of Taunton, where Blake, who not long before had defended Lyme against all the efforts of the Royalists to take it, was now holding out to the last with scanty protection from the fortifications he had improvised. The Committee's orders, necessary perhaps at first, were persisted in even after it was known that Charles had been joined at Oxford by the field army which had hitherto protected the besiegers of Taunton in the West, and that, whilst a much smaller force than eleven thousand men would be now sufficient to raise the siege, every soldier that could be spared was needed farther east. The next blunder of the Committee was even worse. Charles had marched to the North with all the force he could gather, in the hope of undoing the consequences of Marston Moor. If there was one lesson which the Committee ought to have learnt from the campaign of the preceding year it was that it is useless to besiege towns whilst the enemy's army remains unbeaten in the field. Yet when every military consideration spoke with no uncertain voice for the policy of following up Charles's army without remission till it had been defeated, the sage Committee-men at Westminster ordered Fairfax to besiege Oxford. Charles, at liberty to direct his movements where he would, had been deflected from his course, and on May 31 had stormed Leicester. The news shook the Committee's resolution to keep the direction of the army in its own feeble hands. On June 2 it directed Fairfax to break up the siege of Oxford. On the 4th a petition from the London Common Council asked that, though the forty days during which Cromwell kept his appointment under the Self-Denying Ordinance had now elapsed, he might be placed at