Use the map to locate the river that the Union Army of the Potomac marching from Cold Harbor had to cross on their way to Petersburg.?

The Union Army of the Potomac marching from Cold Harbor had to cross the James River on their way to Petersburg. This river was a significant geographical obstacle during the Civil War, impacting troop movements and strategies. The crossing was crucial for the Union forces as they sought to besiege the Confederate stronghold at Petersburg.