The opening two pages tell a brief history of warfare so it takes a while to get to the main plot. Then again, it's illustrated by Severin, so who's complaining?
Eventually we meet our mysterious narrator, who turns out to be an inanimate object.
That's right, the trench itself tells the story of World War I. It's a very French trench at that, as it has no love for the Germans who wind up occupying it late in the story.
Finally, the arrival of the US forces to drive the Germans from the trenches and the establishment of tanks brings an end to World War I.
So, it's a happy ending...? Happy in that trench warfare is no more, but I don't know how pleased those missile-filled skies with a mushroom cloud make me feel...