The first of a four-part series.
Four years after Harmony, a rogue Changeling force, not led by Chrysalis but by a mysterious terrorist known as Chitin, begins to attack several cities. The Military of Equestria does not take it seriously until it's too late, instead leaving citizens of outlying cities to defend themselves, or organize militias. By the time they have hit Canterlot, they also have Manehattan's population either dead, exiled or imprisoned. Baltimare has organized a resistance, but most of them are imprisoned or dead as well. The operators are unprepared for invasion, the military base being one of the first places hit by artillery, so a lot are left with what they can find off of dead soldiers. This specifically follows the exploits of Lance Corporal Allezeite Flashfire, Lance Corporal Divine Intervention, Private Orgullo, Private Qimayat and Private First Class Honeybee. They are all..to put it nicely, adequate soldiers, and as the story progresses, a lot of them start showing symptoms of PTSD.
The story also goes to the point of ponies outside their fireteam, to show different aspects of the war.