Ever since the Earl of Lanark's march to the borders to meet Munro, Archibald Campbell, 1st Marquess of Argyll had been busily employed in raising men in his own territory to assist the Covenanters. Shortly afterwards, Munro and his clansmen who acted as the Earl of Lanark's advance force defeated the forces of the Marquess of Argyll at the Battle of Stirling (1648). Munro had moved in on his own initiative and succeeded in entering Stirling before any of Argyll's commanders were aware of his presence. Munro even personally kicked down a postern door to chase out Argyll's men. Argyll lost about 200 men in the battle. After this victory, Munro urged Lanark to continue and attack David Leslie, but he was overruled and in the following weeks the Earl of Lanark made peace with the Marquess of Argyll and with Leslie.