The "war" against the Fallen is ongoing. The battle of Twilight Gap was just an event where the House of Devils and Kings and Winter formed an alliance against the City. That's kind of a big deal as Fallen houses typically hate each other so it not expected for them to work together. This alliance was broken at the Twilight Gap, at the cost of many Guardians, and the houses all went back to hating each other. It important mostly because a bunch of people died and it was close to the City. Then Feizel Crux looted all the corpses and turned them into Rocket Launchers.