"Beware the leader who bangs the drums of war in order to whip the
citizenry
into a patriotic fervor, for patriotism is indeed a double-edged
sword. It
both emboldens the blood, just as it narrows the mind. And when the
drums of
war have reached a fever pitch and the blood boils with hate and the
mind
has closed, the leader will have no need in seizing the rights of the
citizenry. Rather, the citizenry, infused with fear and blinded by
patriotism, will offer up all of their rights unto the leader and
gladly so.
How do I know? For this is what I have done. And I am Caesar."

- Julius Caesar


I think that's right. Here's a recent newspaper column about the
problem with getting people so whipped up with hate that they lose
their minds.

http://www.indystar.com/articles/4/098743-5314-021.html