Parliament’s spectacular victory at Naseby, in June 1645, was militarily and politically decisive. The destruction of the king’s veteran infantry and the parliamentarians’ capture of so many royalist officers meant that Charles could not rebuild his army into a force that could stand up against the New Model Army in open battle. Cromwell’s superb handling of the parliamentary cavalry and his defeat of Rupert’s mounted regiments removed the aura of superiority that had surrounded the royalist cavalry since the beginning of the Civil War. Henceforth, the Ironsides, as the royalists derisively had called Cromwell’s troopers, seldom lost a skirmish against Cavalier horsemen. This situation allowed Fairfax to march most of his army to the southwest while leaving a relatively small force to hold in check the royalist garrison in Oxford.