Two way radio changed warfare forever. Before this invention allowed commanders and troops to communicate they tried all sort of devices and methods: carrier pigeons, couriers, smoke signals, flags … hand waving (in WWI airplanes).

Hitler’s invasion of Poland and France showed how tanks and airplanes could cooperate perfectly via radio in the so called Blitzkrieg. The polish army hardly had any tanks anyway, but the French had tanks - but these were not equipped with radio and they had not developed any new tactics since WWI.