...minute, and then commenced a close pursuit. The enemy retreated, firing upon us at every chance, while our advance kept close upon them. Thus they were driven from the Gap to Haymarket, thence to Gainesville , thence to New-Baltimore , from which place they retreated to Warrenton. As there are two roads from New-Baltimore to Warrenton, and there was danger of the enemy leading us on by one, and then com...