A few that I like:

"The quickest way of ending a war is to lose it."
George Orwell

"Never, never, never believe any war will be smooth and easy, or that anyone who embarks on the strange voyage can measure the tides and hurricanes he will encounter. The statesman who yields to war fever must realize that once the signal is given, he is no longer the master of policy but the slave of unforeseeable and uncontrollable events."
Winston Churchill (this should have been read in 2001 and 2002)

"I must study politics and war that my sons may have liberty to study mathematics and philosophy. My sons ought to study mathematics and philosophy, geography, natural history, naval architecture, navigation, commerce and agriculture in order to give their children a right to study painting, poetry, music, architecture, statuary, tapestry, and porcelain."
John Adams

"The world has achieved brilliance without wisdom, power without conscience. Ours is a world of nuclear giants and ethical infants. We know more about war that we know about peace, more about killing that we know about living."
GEN Omar Bradley

"War and culture, those are the two poles of Europe, her heaven and hell, her glory and shame, and they cannot be separated from one another. When one comes to an end, the other will end also and one cannot end without the other. The fact that no war has broken out in Europe for fifty years is connected in some mysterious way with the fact that for fifty years no new Picasso has appeared either."
MILAN KUNDERA