The critical intelligence for the Union Army at Gettysburg was provided by Union cavalry scouts.

Under the leadership of General John Buford, the cavalry was crucial in collecting intelligence on Confederate movements and positions before the battle. Their reconnaissance efforts provided the Union Army with valuable insights into the strength and intentions of the Confederate forces. Buford's prompt reports enabled Union commanders to make well-informed decisions regarding defensive placements, which ultimately laid the groundwork for a successful strategy during the battle and significantly influenced the outcome at Gettysburg.