Counters for Walton’s Brigade of the Confederate Reserve Artillery. The Washington Artillery has the distinction of being the oldest Louisiana military unit as well as the “only unit that fought in the war between the states that is still in existence” (http://jane-williams.me.uk/wa/history.cfm)
Although only a major, Walton appears to have been organizationally equivalent to Pendleton (except for the number of batteries at his command).
With this Brigade, the Confederate OOB is complete. There appear to be other minor units around Richmond at this time, but they are either too far away (Drewry’s Bluff), reorganizing or too dispersed (poorly organized militia). Now it’s on to the Union!