The Second Italian War began when King Louis XII of France pressed his claim on the thrones of Milan and Naples. Louis had a claim to the thrones through his paternal grandmother and in 1499, he invaded Italy. He took Milan, Genoa, and Naples. 

When Duke Lodovico Sforza was overthrown, Leonardo da Vinci fled Milan with his assistant and friend to Venice. In Venice he was employed as a military architect and engineer. He designed methods of defending the city from naval attack. 

Louis was driven out of Naples in 1503 by Spain after a defeat at Cerignola. The battle of Cerignola was the first battle in history won by gunpowder small arms.

Britannica, The Editors of Encyclopaedia. “Italian Wars.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 4 Mar. 2016, www.britannica.com/event/Italian-Wars.

“Italian War of 1499–1504.” Wikipedia, Wikimedia Foundation, 3 Feb. 2019, en.wikipedia.org/wiki/Italian_War_of_1499%E2%80%931504.