General McClellan had been on the downward slope for some time. In October 1861, he was general-in-chief of all the Union armies and leader of the Army of the Potomac. In April 1862, Lincoln removed him as general-in-chief, but kept him as general of the Army of the Potomac. Now, in July 1862, Lincoln brought Major-General Henry Halleck from the West, making him general-in-chief. McClellan temporarily was replaced by Major-General John Pope, also brought from the Western theater.

Pope had an unfortunate personal style. On first arriving to take the command, he issued a blustering address to the troops, declaring that he came from the Western department, which had only known victories. This was far from the case, and some men may have laughed, but others took offense. For the moment, Pope assembled the new Army of Virginia, protecting Washington, D.C., while McClellan continued to command the Army of the Potomac.