@Walter Hinteler,
We take that route at least twice a year, from Calais down to Geneva in a straight a line as possible. It takes you right through the centre of where the battle(s) took place, Bethune, Vimy Ridge, Arras, Cambrai, StQuentin.
Each time we're either starting out and wanting to make good progress, or coming back up and have a ferry to catch.
We have stopped to have a look around on one occasion, and very quickly found a military cemetery in the middle of nowhere. Wheat fields all around, skylarks and beautiful blue sky. You wouldn't have a clue as to the carnage, apart from the lack of really old trees and buildings.
We've promised ourselves a full week or so round there soon.