at a crucial moment , confederate maj. gen. a. p. hill 's division arrived Arriving from harpers ferry and launched Process_start a surprise counterattack Attack , driving Preventing_or_letting back burnside and ending Process_end the battle Hostile_encounter .

rock historian glenn a. baker and bob Body_movement king wrote Writing `` australian made Creating , gon na have a good time tonight : the authorised Preventing_or_letting documentary of the event '' in 1987 with detailed notations by baker and photographs by king .