" As a whole, and at times, the efficiency of the truly national leader consists primarily in preventing the division of the attention of a people, as always concentrating it on a single enemy. The more uniformly the fighting will of a people is put into action, the greater will be the magnetic force of the movement and the more powerful the impetus of the blow. It is part of the genius of a leader to make adversaries of different fields appear as always belonging to one category only, because to weak and unstable characters, the knowledge that there are various enemies will lead only too easily to incipient doubts as to their own cause.

As soon as the wavering masses find themselves confronted with too many enemies, objectivity at once steps in, and the question is raised whether actually all the others are wrong and their own nation or their own movement alone is right.

Also, with this comes the first paralysis of their own strength. Therefore, a number of essentially different enemies must always be regarded as one in such a way that in the opinion of the mass of one‘s own adherents the war is being waged against one enemy alone. This strengthens the belief in one‘s own cause and increases one‘s bitterness against the attacker. "

― Adolf Hitler , Mein Kampf