Answer:
marching through neutral Belgium
Step-by-step explanation:
The Germans played tactically very good when they decided to invade France. Instead of going through the Ruhr area, the Germans decided to go around the French defenses, get into their territory, and to perform quick unexpected attacks on them. This was achieved by quickly and without any warning invading the neutral Belgium. The German troop quickly marched through Belgium and entered in France where the French did not expected and didn't had enough military to defend. The Germans quickly managed to take over part of the French territory and then systematically art by part they invaded all of it.