Freiedrich von Hohenzollern (Frederick the Great), while still the heir apparent, wrote a work which has come to be known as
The Anti-Machiavel, and in which he describes in detail the situations in which he considered a pre-emptive war to be justified. He was, of course, much concerned with the security of Prussia, a state which he described justifiably as defenseless against invasion. Predicated upon his notion of the duty of a Prince to the People, he contended that in those situations in which an enemy would likely invade, the Prince should seize the initiative to attack first, and carry the war to the enemy, rather than suffer the destruction attendant upon an invasion. He also contended that such pre-emptive war were justified to secure the national interest. In the latter case, this was his justification for attacking the holdings of the Austrian Archduchess, Maria Theresa, shortly after both he and she acceded to their respective thrones (their fathers died within a few weeks of one another).
It would seem that the contention of self-defense is the
causus belli cited by the current administration for the invasion of Iraq; their critics, of course, say this is disingenuous, contending that it is national interest served in such a war, and the more critical contending that this has to do with cronyism and the advantage to be enjoyed by a select few.