Confederacy (Cs Army of Northern Virginia, 82,507 men under Lee) attacked USA (US Army of the Potomac, 78,902 men under Mcclellan) in Virginia. The CAA Database of Battles records 3.5 hours of fighting on a front of 1.6 km, a frontal attack against hasty defense, and that USA held. Losses: Confederacy 5,355 (6%), USA 3,214 (4%).
This plan is generated from those figures. It shows the shape of the battle the database describes: the size and width of the armies, the plan of attack and the outcome. It does not show where the units actually stood.