Question

What are two big mistakes McClellan made that cost him a victory over Lee at Antietam?

-He was surprise-attacked by Lee.
-He thought Lee's army was much smaller than it was.
-He failed to use one-third of his army.
-He kept his headquarters too far from the battlefield.

Answer 1

Your answer Is D -He kept his headquarters too far from the battlefield.

Answer 2

The answers are C and D. Hope this helped. But it's probably too late given the question's age.