Once the Treaty of Breda had been signed, the Scottish Parliament started levying men to form a new army, under the command of the experienced general David Leslie. Their aim was to increase their forces to 36,000 men, but that number was never achieved; by the time Cromwell entered Scotland, Leslie had some 8,000–9,500 infantry and 2,000–3,000 cavalry, although these numbers fluctuated during the course of the campaign. The government instituted a commission to purge the army of anyone suspected of having supported the Engagement, as well as men considered sinful or undesirable. This was opposed, unsuccessfully, by much of the Scottish nobility and the experienced military leaders, including Leslie. This purge removed many experienced men and officers, and the bulk of the army was composed of raw recruits with little training or experience.