There’s this fantastic (bit of sarcasm here) movie ‘Starship Troopers’, where humanity (the Federation) has to fight against an alien species (the “Arachnids”, also called ‘Bugs’).
First mankind suffers much loss as the Bugs seem to outsmart and outnumber them. At some point they realize there’s there’s a ‘brain-bug’, that is the mastermind behind the fight against the humans, creating the strategy and leading the army of Bugs. If they take out the brain, they defeat the Bugs. With some coincidence a few of the main characters find the brain-bug in a tunnel system. After a short fight the brain-bug eventually gets captured and victory against the Bugs is now only a matter of time.
Take out the brain and you take out it’s army.
Do you know what or who is the brain-bug behind the force your fighting? Once captured, you can easily deal with it’s minions.