Lyric discussion by DetroiToledo 

Cover art for Maginot Line lyrics by Few and Far Between

I'm thinking metaphor (big shock, eh). Comparing his preparations, etc for his life to France's Maginot Line from the 1930s-40s. No matter how great you think you're doing, there's a potential "blitzkrieg attack" that can tear right through (or pass around) all of your defenses. Basically, my summation for the meaning is "life throws us curveballs when we're sitting on fastball."