Albert Einstein, from the Quotemaster:
Heroism on command, senseless violence, and all the loathsome nonsense that goes by the name of patriotism – how passionately I hate them!
And a bonus, also from the Quotemaster. Solzhenitsyn:
Violence can only be concealed by a lie, and the lie can only be maintained by violence. Any man who has once proclaimed violence as his method is inevitably forced to take the lie as his principle.
Waterboarding and Guantanamo, anyone?