Andries Roonie meets with Gen. Lee near Orange Courthouse and demonstrates the AK-47 for him and his aids. It isn't until much later that Lee gets a (stolen) copy of "Life's Picture History of the Civil War."

The South first makes use of the AK in The Wilderness and achieves both tactical and strategic victory.

(an aside - found this comment about Longstreet as I was looking up The Wilderness

"Like a fine lady at a party, Longstreet was often late in his arrival at the ball. But he always made a sensation and that of delight, when he got in, with the grand old First Corps sweeping behind him as his train.
Private William Dame, Richmond Howitzers")