The eastern troops left Philadelphia on Friday night and arrived at the Union Depot on Saturday afternoon, tired and hungry. After a scant and hasty lunch they were placed out along the tracks to the roundhouse where the great bulk of the mob was assembled. In order to secure and protect the building and tracks it was necessary that the crowd should be forced back. When the troops undertook this movement some stones were thrown and a few soldiers were hit. Then one of the subordinate officers gave an order to fire, and about twenty persons were killed and thirty wounded, three of whom were children. When the rioters beheld their associates attacked, their rage passed all control, and the troops were closed in upon and driven into the roundhouse. Encouraged by this retreat, the mob took steps to burn them out. Many cars loaded with whisky and petroleum were set on fire and sent down the track against the building, and fire was opened on it with a cannon which the crowd had seized from a local armory. General Brinton came personally to one of the windows of the roundhouse and appealed to the mob to desist, warning them that if they did not he must and would fire. The rioters paid no attention to his appeal, but continued their assaults, whereupon General Brinton gave orders to his men to fire at those who were handling the cannon, and several of them were killed and wounded. Incendiarism, having been inaugurated, went on through the night, whole trains being robbed and then burned. The troops held their position until Sunday morning, and then retreated out Penn Avenue to Sharpsburg, where they went into camp.