Why Btonze Age?

[abaris]

It's not as simple as knowing whether there are roads.   It takes one good quality road to support just a single Corp on the offensive.  A major land offensive would involve hundreds of thousands of vehicles.  Tracked vehicles like tanks quickly tear up most roads.  So requirement for supporting an mechanized offensive is even higher.  The French didn't believe the number and quality of roads in the Ardennes were sufficient to support more than a couple of division.

German veterans went on record calling it the biggest traffic jam in history.

The German success was not so much a German victory but a French failure. Since this was yet another instance where the troops were extremely vulnerable to airstrikes that didn't happen.