Commanders of the Army of the Potomac
1861-1865

Abraham Lincoln
Commander-in-Chief
1861-1865

Winfield Scott General-in-Chief 1861

George B. McClellan General-in-Chief 1861-1862

Henry Halleck General-in-Chief 1862-1864

Ulysses S. Grant General-in-Chief 1864-1865

Irvin McDowell¶ 1861

George B. McClellan 1861-1862

Ambrose P. Burnside 1862-1863

Joseph Hooker 1863

George G. Meade 1863-1865

¶ The name "Army of the Potomac" was first coined by George McClellan. While Irvin McDowell did not command the Army under that name, he did command the same troops before being relieved by McClellan.

John Pope never formally commanded the Army of the Potomac. After the Peninsula Campaign, President Lincoln ordered the bulk of McClellan's troops transferred to Pope's Army of Virgina; McClellan was an army commander without an army. Following Pope's defeat at the Second Battle of Bull Run, the troops from the Army of the Potomac were transferred back to McClellan. When challenged about his continued use of McClellan, Lincoln responded, "We must use the tools we have."

http://einstein.human.cornell.edu/ACW/aopcommand.html