The army was strengthened; but no efforts could spur its leader into activity. Essex had learned his trade in the Thirty Years War; and like most professional soldiers he undervalued the worth of untrained levies. As a great noble, too, he shrank from active hostilities against the king. He believed that in the long run the want of money and of men would force Charles to lay down his arms, and to come to a peaceful understanding with the Parliament. To such a fair adjustment of the claims of both a victory of the Parliament would, he thought, be as fatal as a victory of the king. Against this policy of inaction Hampden struggled in vain. It was to no purpose that he urged Essex to follow Charles after Edgehill, or to attack him after his repulse before Brentford. It was equally to no purpose that he urged at the opening of 1643 an attack upon Oxford. Essex drew nearer to the town indeed; but at the news of the queen's junction with her husband, and of the successes of the Cornishmen, he fell back to his old cantonment about Thame. Hampden's knowledge of the country warned him of danger from the loose disposition of the army, and he urged Essex to call in the distant outposts and strengthen his line; but his warnings were unheeded. So carelessly were the troops scattered about that Rupert resolved to beat up their quarters; and leaving Oxford in the afternoon of Saturday, the 17th of June, he seized the bridge over the Thame at Chiselhampton, and leaving a force of foot to secure his retreat, threw himself boldly with his horsemen into the midst of the Parliamentary army. Essex with the bulk of his men lay quietly sleeping a few miles to the northward at Thame as Rupert struck in the darkness through the leafy lanes that led to the Chilterns, and swooped on the villages that lay beneath their slopes. At three in the morning he fell on the troops quartered at Postcombe, then on those at Chinnor. Here some fifty were slain, and more taken prisoners, as they sprang half-naked from their beds. The village was fired, and Rupert again called his men together to pursue their foray. But the early summer sun had now risen; it was too late to attack Wycombe as he had purposed; and the horsemen fell back again through Tetsworth to secure their retreat across the Thame.