Roster of Confederate Soldiers, 1861-1865, shows:

Grubbs, A.J. GA 13th Inf. Co.C

as well as

Grubbs, G. GA 13th Inf. Co.F

13th GA Inf Reg organized for the war 7/8/1861 - mustered in at Griffin - surrendered at Appomattox Court House 4/9/1865
Battles:
Whitemarsh and Wilmington Islands [detatchment] - 3/30-31/1862
Whitemarsh Island [skirmish] - 4/16/1862
Shenandoah Valley Campaign - May-June 1862
Seven Days Battles - 6/25-7/1/1862
Gaines' Mill - 6/27/1862
Malvern Hill - 7/1/1862
Cedar Mountain [guarding trains] - 8/9/1862
Bristoe & Manassas Junction - 8/26-27/1862
2nd Bull Run - 8/28-30/1862
Chantilly - 9/1/1862
Harpers Ferry - 9/12-15/1862
Antietam - 9/17/1862
Boteler's Ford - 9/19/1862
Fredericksburg - 12/13/1862
Chancellorsville - 5/1-4/1863
2nd Winchester - 6/14-15/1863
Gettysburg - 7/1-3/1863
Snicker's Gap - 7/17/1863
Bristoe Campaign - Oct 1863
Mine Run Campaign - Nov-Dec 1863
The Wilderness - 5/5-6/1864
Spotsylvania Court House - 5/8-21/1864
North Anna - 5/23-26/1864
Cold Harbor - 6/1-3/1864
Lynchburg Campaign - May-June 1864
Harpers Ferry - 7/6/1864
Maryland Heights - 7/9/1864
Monocacy - 7/9/1864
Winchester - 8/11/1864
3rd Winchester - 9/19/1864
Fisher's Hill - 9/22/1864
Cedar Creek - 10/19/1864
Petersburg Siege [from Dec] - May-June 1864-April 1865
Hatcher's Run - 2/5-7/1865
Appomattox Court House - 4/9/1865

Compendium of the Confederate Armies - South Carolina and Georgia, by Stewart Sifakis, pages 210-212