"Then the 28th relieved the 18th [Virginia], [on the right flank of Pickett’s Brigade] which had run short of ammunition.
Treacherous conduct by the Federals confused the issue when the 8th Alabama arrived to strengthen the right flank of the newly positioned 28th Virginia. As the 8th Alabama prepared to fire a volley into the enemy ranks, a Union officer cried out, “We are friends, don’t fire,” and had his men hold their hands in the air. As Colonel Irby of the 8th Alabama motioned for his men to hold their fire, “the accomplished cowards poured in a deadly volley, killing the colonel and many of his men.” The 8th [Alabama] returned fire, causing the Federals to take to their “heels”."
I am unable to find the source of this information, which appears to be from another reference. Can someone provide the source of this information? Is it from a soldier's letter or someone's official report? Any help would be appreciated. (By the way, it is different from the description of the event that is recorded by Hilary Herbert in his history of the 8th Alabama.)