Is There a Fortress in France?

I feel as though there was all this fortress construction that they would later put to such great use in the beginning of World War II. But I do really want to do a episode or a series in the fall of France because it seems like nobody really talks about it. Everybody likes to assume that like Germans drove around the Maginot line and the French immediately surrendered rather than like the French military just getting fucking mangled trying to defend themselves. It really does seem to be a part of World War Two that people just gloss over.