These are some ideas  for Blades in the Dark, when non-player gangs are at war.

Right before or right after a job, roll a fortune roll for each warring party. Did the players do something to give an advantage to one side or the other? If so, give one side a major advantage or another side a major disadvantage. If what they did is known, they take -1 faction status with the gang they hindered. If what they did is a crucial part of a gang’s success, they take +1 faction status.

War creates opportunities for jobs but eventually it causes problems for everyone.

Every time one side rolls a 6 in their fortune roll, heat for all jobs is +1.

Gang-moot gathers to discuss ending the war clock

A 6 count clock begins ticking for local gangs looking for ways to end the war quickly; this conflict has begun to cut into everyone’s bottom line as the local papers run stories on out of control gang violence and Bluecoats crack down and begin to edge closer to getting military hardware. Ending the war might mean getting together reasonable leaders who can bring the warring parties together in a neutral space or it might mean throwing everyone’s weight behind one side and wiping the other out. Players can dedicate downtime actions towards putting ticks on this clock (or taking them off). If they put several ticks on the clock, they will have a say on who is invited and who is left out.

Art

Clark, Walter Appleton, Artist. He gripped Prosper by the head. [?] Photograph. Retrieved from the Library of Congress, <https://www.loc.gov/item/2010715410/&gt;.

The Miriam and Ira D. Wallach Division of Art, Prints and Photographs: Photography Collection, The New York Public Library. “Wm. Hawes in front of jewelry store with intricate clock.” The New York Public Library Digital Collections. http://digitalcollections.nypl.org/items/510d47e0-69ca-a3d9-e040-e00a18064a99