Answer:
Johnston and Lee attacked McClellan - Battle of Seven Pines
Commanded Army of the Potomac - McClellan
Kept Union Army in Washington, D.C. - "Stonewall" Jackson
Commanded Army of Virginia - Robert E. Lee
Commanded Union forces in the East - General Halleck
Defeated Pope at the 2nd Battle of Bull Run - Jackson and Lee
Bloodiest single day battle - Antietam