Hitler had to learn the true nature and the power of nonviolent resistance the hard way. These were Hitler's words in 1943, admitting privately to his lieutenants the difficulties of ruling the conquered regions such as Denmark, Norway, Czechoslovakia, etc., where people were using nonviolent non-cooperation means to resist the Nazi occupation.
"One cannot rule by force alone... For, in the long run, government systems are not held together by the pressure of force, but rather by the belief in the quality and the truthfulness with which they represent and promote the interests of the people."