50 guns in 9 batteries of the Artillery Reserve were already in position to defend against the attacks from Hood, McLaws and Anderson's divisions.
3 batteries from the 1st US Regular Brigade (18 guns)
4 batteries from the 2nd Volunteer Brigade (22 guns)
2 batteries from the 4th Volunteer Brigade (10 guns)
The majority were in support of III Corp
All 4 batteries of the 1st Volunteer Brigade from the reserve, plus 1 battery from the 4th Brigade (28 guns) were posted on the Wheatfield Rd. facing south.
The remaining 4 batteries supported the center and right in position behind troops along the Emmitsburg Rd.
The majority of the guns from the Reserve were in action against McLaw's and Andersons' divisions.
When the Peach Orchard salient begin to collapse from the west along Emmitsburg RD, all the batteries facing south without infantry support withdrew to the rear.
You should read Bradley Gottfried's books "Maps of Gettysburg" and Artillery of Gettysburg" to do an accurate game.
Kim