Unless you are totally familiar with the strange morass that was the Korean War, the results of which are this day evident in a divided county, it might help to zip over to Wikipedia and get an overview of the reasons for the conflict, some historical background as backup, as The Front Line tosses the viewer into the heat and broil of battle at once, and it helps to know what's going on historically.
That said, this is an amazingly powerful and kinetic document about power and honor and the nature of being a soldier; it is told from the viewpoints of one main character sent to join a problematic unit where it appears that there might be an embedded traitor; along with the viewer, the character discovers who in the unit holds what secrets, who has a sense of perspective, who cannot take orders and even unearths a past event which explains the odd behavior of so many in the unit. All this while having to engage in brutal battle, often hand-to-hand, on a daily battle, an immersion into human beings expected to be killing machines.
Like Kubrick's great anti-war classic, Paths of Glory, The Front has the men engaged in which is essentially a suicide mission to save a small inch of land; in Paths of Glory, it was the "Anthill," held by the Germans; in this film, Aerok Hill, still in dispute. This is a dark film with occasional glimmers of humanity, but no glorification of war.