McClellan discovered General Robert E. Lee's battle plan.
Obviously, infiltration and access to battle plans allow for the opponent to figure out what their opponent's plans are, thus giving McClellan the victory at Antietam.
Hope this helps!
We need to see the following to answer this....
1. A dead fish
2. B first cities in north america
3. C kachinas
4. A bones were used as h- (brainly won't allow the word)
5. C hohokam