Halting just outside the village, Harry formed his men with a front across the whole road, and directed the lines to advance, twenty yards apart. Then, placing himself at their head, he gave the word, and charged down the street upon the Roundheads. The latter, occupied by their attack upon the houses, were unconscious of the presence of their foe until he was close upon them, and were taken utterly by surprise. The force of the charge was irresistible, and the Roundheads, dispersed and on foot, were cut down in all directions. Groups of twos and threes stood together and attempted resistance, but the main body thought only of regaining their horses. In three minutes after the Royalists entered the village the surviving Roundheads were in full flight, hotly pursued by the victorious Cavaliers. These, being for the most part better mounted, overtook and slew many of the Roundheads, and not more than half the force which had set out returned to their quarters at Didcot. The pursuit continued to within half a mile of that place, and then Harry, knowing that there was a force of Roundhead infantry there, drew off from the pursuit, and returned to Chalcombe. He found that more than half of Sir Ralph Willoughy's men had been killed, many having been cut down before they could betake themselves to their arms, those quartered in the inn, and at two or three of the larger houses, having alone maintained a successful resistance until the arrival of succor. 
What forces did the Roundheads have?
On horse