How did the Lost Order #191 help the Union?
It guaranteed them a victory over the South at Antietam
It forced the Confederates to unify their armies at Sharpsburg.
O McClellan knew what the Confederates were going to do ahead of time.
It showed that Lee had a lot more troops than McClellan first thought.

The correct answer is McClellan knew what the Confederates were going to do ahead of time.

Explanation: General Robert E. Lee issued an order # 191, which somehow got lost, right before the Battle of Antietam. The order was found by Union forces of the 27th Indiana troops on the Best Farm in Maryland. Lee, not knowing the order was lost, continued with the plan. McClellan having the lost plan in his hands, used it to defeat Lee,

answer; (religion)