Capture

Capture is a side quest in the Fallout 4 add-on Nuka-World.

Detailed walkthrough
Speak to Shank and choose the settlement that the player character wants to convert into a raider outpost. Go to the location and kill every settler that lives in the settlement and kill all of the minutemen protecting the settlement. After this, the player character needs to open up the workshop and build the gang's signal flag.