The firing had been so rapid and so heavy that the whole field in front of the fort was covered with smoke, through which they caught only the gleam of bayonets and glimpses of battle flags. But they knew that the Northern troops were retiring, carrying with them their wounded, but leaving the dead behind. Harry, excited and eager, was about to leap upon the crest of the earthwork, but Colonel Talbot sharply ordered him down. "You'd be killed inside of a minute!" he cried. "Carrington is out there with the guns! As soon as their troops are far enough back he'll open on us with the cannon, and he'll rake this fort like a hurricane beating upon a forest. Only the earthworks will protect us from certain destruction." He sent the order, fierce and sharp, along the line, for every one to keep under cover, and there was ample proof soon that he knew his man. The Northern infantry had retired and the smoke in front was beginning to lift, when the figure of a tall man in blue appeared on a hillock at the edge of the forest. Harry, who had snatched up a rifle, levelled it instantly and took aim. But before his finger could pull the trigger Colonel Talbot knocked it down again. "My God!" he exclaimed. "I was barely in time to save him! It was Carrington himself!" "But he is our enemy! Our powerful enemy!" "Our enemy! Our official enemy, yes! But my friend! My life-long friend! We were boys together at West Point! We slept under the same blanket on the icy plateaux of Mexico. No, Harry, I could not let you or any other slay him!" The figure disappeared from the hillock and the next moment the great guns opened again from the forest. The orders of Colonel Talbot had not been given a moment too soon. Huge shells and balls raked the fort once more and the defenders crouched lower than ever in the trenches. Harry surmised that the new cannonade was intended mainly to prevent a possible return attack by the Southern troops, but they were too cautious to venture from their earthworks. The Invincibles had grown many years older in a few hours. When it became evident that no sally would be made from the fort, the fire of the cannon in front ceased, and the smoke lifted, disclosing a field black with the slain. Harry looked, shuddered and refused to look again. But Colonel Talbot examined field and forest long and anxiously through his glasses. "They are there yet, and they will remain," he announced at last. "We have beaten back the assault. They may hold us here until a great army comes, and with heavy loss to them, but we are yet besieged. Carrington will not let us rest. He will send a shell to some part of this fort every three or four minutes. You will see."