in American history. While almost all of Lee's army had been heavily engaged, about a third of the Union forces had not entered the action. Lee's army remained in position on September 18, and McClellan did not order an assault, despite having a significant number of fresh troops. That night, the Confederates began their retreat, aiming for Martinsburg, Virginia. After crossing the Potomac River, Lee left his artillery chief, Brigadier General William N. Pendleton, to hold a rear guard at Boteler's Ford. Pendleton, a former clergyman, had a questionable military reputation and was unpopular with his men. He also had no prior experience commanding infantry. In addition to Boteler's Ford, Pendleton also had to cover another ford to the south and Shepherd's Ford to the north. A small cavalry force was available to cover the southern ford, and Pendleton dispatched an artillery battery and a small infantry force to Shepherd's Ford. Preservationist Frances E. Kennedy states that Pendleton had two brigades and 45 cannon available, while historian Peter S. Carmichael states that he had only 600 men (some of whom were unarmed) and about forty cannons to work with. Historian Shelby Foote gives a cannon count of 44. Battle September 19 Pendleton had excellent terrain to defend at Boteler's Ford: the Virginia side of the Potomac had high cliffs that would be difficult to assault. He placed his 600 men, from the brigades of Alexander R. Lawton and Lewis A. Armistead (led by replacement officers as both Lawton and Armistead had been wounded at Antietam), at the ford itself, while aligning 33 cannons in positions covering the ford. Shorter-range cannons were placed close to the river, while longer-range guns were positioned further back. Advantageous positions for 11 cannons could not be found, so Pendleton did not deploy them. The Confederates may have also had a small reserve. Lee's orders for Pendleton presented two scenarios: if Union activities against Boteler's Ford were limited to artillery firing, Pendleton was to withdraw on the morning of September 20, but if a major Union attack was made, Pendleton was to fall back on the evening of September 19. On the morning of September 19, Union cavalry and artillery commanded by Alfred Pleasonton approached Boteler's Ford and began an artillery duel. In the late afternoon, the Union V Corps, commanded by Fitz John Porter, arrived. Porter deployed 15 cannons, which were able to silence the