The Battle of Malvern Hill, was the first time during the Seven Days that the entire Army of the Potomac was united on the same field.
The Army of the Potomac was the principal Union Army in the Eastern Theater of the American Civil War. It was created in July 1861 shortly after the First Battle of Bull Run and was disbanded in June 1865 following the surrender of the Confederate Army of Northern Virginia in April. Lee's sudden and violent attacks in the last week of June 1862 caught General George B. McClellan completely off guard. Almost immediately, "Little Mac" determined that he could no longer take Richmond, and sent his army into a full retreat toward James. Along the way, elements of the Army of the Potomac stood bravely, trying to slow Lee's advance, but McClellan never deployed the bulk of his army to stop the Rebel attack.
On July 1, 1862, for the first time that week, the Army of the Potomac - all five Union legions were in the same place at the same time. The open nature of Malvern Hill itself allowed the Yankees to deploy their entire massive army in a way they hadn't since the beginning of the seven days. However, elements of the three corps were detailed to protect the Confederate right flank. Even with all his troops in one place, McClellan did not use his entire army. The Army of the Potomac is one of the facts about the Battle of Malvern Hill.
