His foolish statements provided his opponents with more 'ammunition' to use against him in the campaign.
She had the 'ammunition' to prove her case. [=she had the evidence she needed to prove her case]
The troops were supplied with weapons and 'ammunition'.
(..) ..Sherlock's a fraud, and people will swallow it because the rest of it's true. Moriarty wanted Sherlock destroyed, right, and you have given him the perfect ammunition. John. I'm sorry. Oh, please! Tell him, would you? I got your message. (..)2012 TvShow: Sherlock Title: The Reichenbach Fall Season: 2 Episode 3