General Stuart at once reported to General Jackson, who requested him to convey the news to General Lee at Sharpsburg. But even now Lee was in great peril. He had with him, on the evening of Sept. 14 when the gaps were stormed, only about 20,000 men; and McClellan’s army of more than 87,000 was advancing rapidly to attack him. Lee had now either to recross the Potomac or to fight a battle north of that river. He decided to make a stand, and on the night of Sept. 14, drew his army across Antietam creek and took a strong position on a range of hills east of the Hagerstown turnpike. Here he waited for Jackson who, by a forced march, came up in time to take position on the left wing on the morning of September 16. Even when reenforced by Jackson, Lee had a much smaller force than McClellan. On the evening of Sept. 16, McClellan attacked Jackson’s wing at the left of Lee’s army, but was repulsed. At early dawn the next day, the attack was renewed and the combat raged all day. When night ended the bloody contest, the Confederates not only held their position, but had advanced their lines on a part of the field. During the entire battle, Stuart with his horse artillery and a small cavalry escort had guarded the open hilly space between Jackson’s left and the Potomac river. General Jackson in his report of this battle said: “This officer (General Stuart) rendered valuable service throughout the day. His bold use of artillery secured for us an important position which, had the enemy possessed, might have commanded our left.” The next day, Lee waited for McClellan to attack, but no movement came from the hostile camp. Finding out through Stuart’s scouts that large bodies of fresh troops were being sent to McClellan, Lee withdrew that night to the south side of the Potomac, and by eleven o’clock the next morning, he was again ready to give battle should the Federals pursue. He had brought off nearly everything of value, leaving behind only several disabled cannon and some of his wounded. While Fitz Lee’s and Munford’s troops were left to protect the retreat of the army, Stuart with a small force had gone up the Potomac to Williamsport, hoping to divert the attention of the Federals from the main body of the army and so enable it to cross the river unhindered. This movement was successful, for large Federal forces were sent against him, yet he maintained his position without reenforcements until the night of September 20, when he recrossed the Potomac in safety. During this short campaign, several interesting incidents occurred. On one occasion, when the Federals were advancing toward Williamsport, a young lady of the town obtained permission to fire a cannon that was about to be discharged. After this, the soldiers always called that cannon “the girl of Williamsport.”