A front line (alternatively front-line or frontline) in military terminology is the position(s) closest to the area of conflict of an armed force's personnel and equipment.
Although the term "front line" first appeared in the 1520s, it was only in 1842 that it was recorded used in the military sense. Its first use as an adjective was from 1915.
Played and recorded by V.E.D., as part of the videogame endings database, whose goal is to catalogue and create the world's largest archive of videogame endings! (what an humble and not ambitious project :D)