This sounds a little dumb now that I'm thinking about it, but I'll ask anyway.

I have the Lord Commander title and an opponent does a military challenge at me. Can I let it go unopposed and then re-direct the against myself and defend it so I can win and steal a power from the attacker?

boben_fett said:

"When an opponent is attacked by another opponent"

Oh duh reading the rules probably helps

I was just looking at the card which didn't say anything about opponents.

"Redirect against yourself one undefended Military challenge each round. If you win the challenge, take one power from the attacker."