Leonardo da Vinci - A letter to the lord of Milan
Time: 1482
Place: Milan, Italy
Details: In a letter of 1482 to the lord of Milan Ludovico il Moro (Ludovico Sforza), Leonardo wrote that he could create all sorts of machines both for the protection of a city and for siege. When he fled from Milan to Venice in 1499, he found employment as an engineer and devised a system of moveable barricades to protect the city from attack.