The monument to the 8th Illinois Cavalry is west of Gettysburg on South Reynolds Avenue. (39.835796° N, 77.249447° W; map) It was dedicated in 1891 by the State of Illinois.
The monument was erected in 1890 on the original location of the monument of the 8th New York Cavalry, which was moved 100 feet to the south to "accurately mark the regiment's main battle line on July 1, 1863." The name on the rear of the monument, "David Diffenbaugh," was the only member of the regiment killed at Gettysburg.
The 8th Illinois Cavalry had 491 men at Gettysburg, of whom David Diffenbaugh was killed, 5 men were wounded and 1 was missing.
Their regimental commander at Gettysburg was Major John Lourie Beveridge, a lawyer from Evanston who went on to become Sheriff of Cook County, congressman, and Governor of Illinois.
The claim of "first shot" made for Lt. Jones was disputed by the 9th New York Cavalry, and despite rulings by the Gettysburg Battlefield Memorial Association, has remained in conflict to this day. Lt. Jones erected his own "First Shot" monument on Chambersburg Pike in 1883.
From the front of the monument:
8th Ilinois Cavalry
1st Brig. 1st Div.
First line of battle
July 1, 1863
Occupied until relieved by 1st Corps.
One squadron picketed ridge east of Marsh
Creek and supported by another squadron
met enemy's right advance,
Lieut. Jones, Co. E, fired first shot as the
enemy crossed Marsh Creek Bridge
From the rear of the monument:
On reforming line Regiment took an
advanced position on Hagerstown Road
Late in the day delayed enemy's advance
by attacking his right flank
thereby aiding the infantry in
withdrawing to Cemetery Hill.
In the evening encamped on left flank.
Buford's Division retired toward Westminster