The Battle of Gettysburg, one of the most decisive battles of the American Civil War, was fought on July 1�3, 1863 near a small Pennsylvania town important for its many road and railroad connections. The Confederate army under General Robert E. Lee consisted of 72,000 men and was organized into corps commanded by Generals Longstreet, Ewell, and Hill and a cavalry corps commanded by General Jeb� Stuart. The Union army commanded by General George G. Meade had about 94,000 men, organized into seven corps and a cavalry corps. This map shows the Confederate and Union positions late on July 2, the second day of the battle. Confederate forces are identified at the corps level, while more detail is provided about the Union side, including the names of some division commanders, breastworks, and cavalry positions. The map was made by William H. Willcox, captain and aide de camp on the staff of General John F. Reynolds, a Union corps commander who was killed on the morning of July 1. Gettysburg had the largest number of casualties of any battle in the Civil War, with about 23,000 killed, wounded, and captured or missing on each side. The battle was a defeat for the Confederacy, as it forced Lee to break off his invasion of the North and retreat back into Virginia.