July 3, 1863: Jennie Wade (20), the only civilian casualty of the Battle of Gettysburg, began preparing biscuits and about 8:30 a.m., while she stood in the kitchen kneading dough, she was struck in the back by a Confederate bullet that had traveled through a wooden door, killing her instantly.
Sadly, Jennie's tragic story does not end there. She was engaged to a Union soldier from Gettysburg, Corporal Johnston "Jack" Skelly, who, unknown to her, had been mortally wounded two weeks earlier in the Battle of Winchester.
Private Wesley Culp, a Gettysburg native fighting for the Confederacy, who had gone to school with both Skelly and Jennie, came across Skelly at a field hospital where the wounded soldier gave him a note to pass on to his fiance, Jennie.
Unfortunately, Culp was also killed and the note never made it back to Jennie.
http://www.army.mil/gettysburg/profiles/wade.html
Answer:
Corporal Johnston "Jack" Skelly-
87th Pennsylvania Infantry Volunteers
Edit - The question asked for not only the regiment but also the company to which Skelly belonged.
Hoosier