No greater advantage by any northern soldier was handed to the South, than that of the rifleman who wounded Joe Johnston on May 31st 1862, removing this incubus from the CSA and putting Lee directly into the saddle when he was most needed.
I have had the idea of doing a sort of "who done it" short story murder-mystery, the basic premise being that Joe Johnston was actually wounded intentionally by friendly fire--one of the South's expert snipers working clandestinely for the Confederate Secret Service--that is, for an inner cabal in the Service in Richmond intent upon getting R. E. Lee in command of the armies in Virginia asap. Johnston was deliberately hit in the shoulder. Ironically, he was shortly after hit by grapeshot in any case. An interesting exploration of the cui bono point of view--for what was clearly a pivotal "accident" in the course of the war--that benefited the South more than anything else conceivable at the time...
(for those of you wondering about Lee appearing by default in the summer of '62, perhaps)