The number varied over the several yeas this field army was in existence. Generally around 110,000 for the last few years, but almost always between 80,000 and 125,000, the high reached in the summer of 1862. The "Army of the Potomac" was the name given to this force in 1862. Many of these units were in the Union force that fought in the First Battle of Bull Run in 1861, before the Army defending Wasington acquired this name. During the last year of the war, in the Siege of Richmond and Petersburg, in addition to the Army of the Potomac other Union units from the Army of the James were on the scene, and the Army of the Shennandoah was cooperating in the Shennandoah Vally just to the west.
The Army of the Potomac mustered somewhere around 93,000 men.
133,868 soldiers of the Army of the Potomac fought 60,892 of the Army of Northern Virginia. You can find much more information on the Battle of Chancellorsville in the Sources and related links section, below.
Army of the Potomac ended in 1865.
Army of the Potomac was created in 1861.
The Battle of Fredericksburg cost the Union Army of the Potomac 1,284 killed, 9,600 wounded, and 1,769 captured/missing.
Major Gen. George Brinton McClellan.
The Army of the Potomac.
General George B. McClellan was a master at training, organizing and gaining almost full loyalty to his soldiers and their commanders. In his attempt to make the Army of the Potomac an unbeatable army, he took about eight months. He was then satisfied they were ready for combat.
Potomac
Army of the Potomac
Army of the Potomac
General George B. McClellan was the first commander of the Federal Army of the Potomac.