I have taken a look at the compiled service records of Confederate Soldiers who served in organization from the state of Georgia. Your Peter Spikes
is listed with this information.

Peter Spikes, 26 Georgia : enlisted at Traders Hill, Georgia on August 15, 1861. He was in (New) Co F, of the Okefenokee Rifles 13 Regiment Infantry.
(also known as Co G 26th Regiment Georgia Infantry). He was listed as (Killed) at Bristow & Manassas Junction on 26 / 27 August.
This is under : List of killed or wounded and missing in Ewell's Division from Aug 22 - Sept 20 , 1862.

http://www.footnote.com/documents/28819013/civil_war_soldiers_confederate_ga