Leonardo da Vinci was not a pacifist (second paragraph). As linked here on Hacker News, he designed weapons of war and bragged how great they would work, He was essentially an "arms dealer."

In his words:

"...I have methods for destroying every rock or other fortress, even if it were founded on a rock, etc. Again, I have kinds of mortars; most convenient and easy to carry; and with these I can fling small stones almost resembling a storm; and with the smoke of these cause great terror to the enemy, to his great detriment and confusion. ..."

http://www.theladders.com/career-newsletters/leonardo-da-vin...