one o'clock before
It was now one o'clock and the men had fought almost continuously since the sun rose . The infantry fire slowly slackened and ceased in the Union right and centre . Burnside , who held the Union left , was ordered to advance by the capture of the stone bridge over the Antietam . But a single brigade under General Toombs guarding this bridge held an army at bay and it was one o'clock before the bridge was captured . Burnside now pushed his division up the heights against Sharpsburg to cut Lee 's line of retreat . The Confederates held their ground with desperate courage , though outnumbered here three to one . At last the grey lines melted and the men in blue swept triumphantly through the village and on its edge suddenly ran into a line of men clad in their own blue uniform .