Attack of Confederate infantry on dismounted Union cavalry begins the collision of armies at Gettysburg

The Armies of Northern Virginia and the Potomac collided at  9:30 a.m. when General Buford's Union cavalry division, fighting dismounted and blocking the north and west roads into Getttysburg, came under attack from General Heth's infantry division of the Confederate Third Corps. Lieutenant Marcellus Jones of the 8th Illinois, commanding a forward picket, is credited with firing the first carbine shot at probing skirmishers to open the battle.  Both sides rushed reinforcements forward during the day and the pivotal three day battle was joined.  (By John Osborne)