Middle Military Division, faced constant pressure to attack Early, but Lieutenant General Ulysses S. Grant warned Union leaders on August 12 that two divisions of infantry had joined Early, and that Sheridan "must be cautious and act now on the defensive" until Grant's actions near Richmond would cause those units to return to the Richmond area. The impending presidential election of 1864 made it necessary to avoid any military disaster that might hamper the re-election of President Abraham Lincoln. Sheridan kept his troops between Early's army and Washington, and fought several small battles—including the Battle of Berryville that ended September 4. After that battle, Early withdrew during the night to the west side of Opequon Creek between Berryville and Winchester, Virginia. Sheridan's troops kept their same positions for the next few weeks, with daily cavalry probes including the capture of the 8th South Carolina Infantry Regiment by a cavalry brigade led by Brigadier General John B. McIntosh. Sheridan's tentativeness caused Early to believe Sheridan was a timid commander. Sheridan's plan During September 1864, Sheridan sought information about Early's troop strength. His scouts discovered Thomas Laws, a slave with a permit to enter Winchester to sell produce, who agreed to carry messages. A schoolteacher named Rebecca Wright, who was living in Winchester, agreed to provide information on Early's troops. From a message written on September 16, Sheridan learned from Wright through Laws that a division of infantry and battalion of artillery, commanded by Major General Joseph B. Kershaw, had left the area to rejoin General Robert E. Lee's Army of Northern Virginia near Richmond or Petersburg. Given the information, Sheridan planned to send his infantry to Newtown on the next day, which would prevent a retreat south by Early. His plan was delayed when Grant directed Sheridan to meet him at Charlestown, and upon returning he changed his plan to accommodate Early sending two divisions to Martinsburg, West Virginia. In Martinsburg, Early became aware of Grant's visit on the morning of September 18, and sent one division to Bunker Hill (slightly north of the halfway point between Winchester and Martinsburg) and the other division (with Early) further south to Stephenson's Depot on the north side of Winchester. Sheridan's final plan was to have cavalry divisions led by Brigadier General Wesley Merritt and Brigadier General William W. Averell attack from the north. From the east, a cavalry division led by Brigadier General