To Ludovico Sforza, Duke of Milan

Having now, most illustrious Lord, sufficiently seen the specimens of all those who consider themselves master craftsmen of instruments of war, and that the invention and operation of such instruments are no different from those in common use, I Shall now endeavor without offending anyone, to explain myself to your Excellency by revealing to your Lordship my secrets and then offering them for your pleasure and approbation to work with effect at the opportune time as well as all those things which, in part, shall be briefly noted below.

  1. I have the kind of bridges that are extremely light and strong, made to be carried with great ease, and with them you may pursue and, at any time, flee from the enemy; and there are others, that are safe, indestructible by fire and battle, easy and convenient to lift and set up; and also methods of burning and destroying those of the enemy.
  2. I know how, when a place is under attack, to eliminate the water from the trenches, and make endless variety of bridges, and covered ways and ladders, and other machines pertaining to such expeditions.
  3. If, because of the height of the banks, or the strength of the place and its position, it is impossible, when besieging a place, to follow a plan of bombardment, I have methods for destroying every castle or other fortress, even if it were built on rock, etc.
  4. I also have other kinds of mortars that are most convenient and easy to carry; and with these small stones can be thrown creating the effect of a storm; and the smoke produced by this will strike terror into the hearts of the enemy to his great detriment and confusion.
  5. And if it should be a sea battle, I have many kinds of machines that are most efficient for offense and defense; I also have vessels which will resist the attack of the largest guns and powder and fumes.
  6. I also have means that are noiseless to reach a designated area by secret and tortuous mines and ways, even if they had to pass under a trench or river.
  7. I will make covered chariots, safe and unattackable, which can penetrate the enemy with their artillery, and there is no body of men strong enough to prevent them from breaking through. And behind these, infantry could advance unharmed and without any hindrance.
  8. In case of need I will make big guns, mortars, and light ordnance of fine and useful forms that are out of the ordinary.
  9. If the operation of bombardment should fail, I would contrive catapults, mangonels, trabocchi, and other machines of marvelous efficacy and unusualness. In short, I can, according to each case in question contrive various and endless means of offense and defense.
  10. In time of peace I believe I can give perfect satisfaction that is equal to any other in the field of architecture and the construction of buildings, public and private, and in directing water from one place to another.

I can execute sculpture in marble, bronze, or clay, and also in painting I do the best that can be done, and as well as any other, whoever he may be.

Again, the bronze horse may be taken up, which is to be to the immortal glory and eternal honor of the happy memory of the prince, your father, and of the illustrious house of Sforza. And if any of the above-named things appear to anyone to be impossible or not feasible, I am more than ready to test the experiment in your park or in whatever place may please your Excellency, to whom I commend myself with the utmost humility, etc.

Leonardo Da Vinci, 1452-1519 Trans. adapted from Julie Conaway Bondanella and Mark Musa, The Italian Renaissance Reader (New York, 1987), 193-195.