Quick history question about the battle of gettysburge?

"In June, Robert E. Lee decided to take the war north. He planned to destroy the railroad bridge at Harrisburg, then "turn my attention to Philadelphia, Baltimore, or Washington as may seem best for our interest." After the long march north, Confederate troops were spread from Chambersburg, through Carlisle, and into York. Towns across southern Pennsylvania were being "explored" for much needed supplies to continue the Southern offensive. While looking in Gettysburg, Pettigrew's brigade spotted Buford's cavalry on a ridge a mile west of town." ok so I read this on a wesite but was kind of confused. Who was the side searching in pennsyvania? The north(union), or south(confederate)