When Israel took vengeance on Midian they sent 12,000 troops (Numbers 31:4) and prevailed. We aren't told how numerous Midian was, only that the spoils includes 32,000 virgin women (31:35). This isn't enough information to go on, but it sounds like either Israel was outnumbered or Midian has some unusual proportions of virgins to non-virgins and women to men.
How numerous was the Midianite army? If large, why didn't Moshe send more soldiers (he had them, per the recent census)? Was there reason to believe that they would be an easy conquest (and maybe that's why Midian sent seducers first)? A commander usually doesn't want to send unnecessary troops (they get tired and become tamei), but he wants to send enough. What's going on in this case?