Michelangelo flees Florence, abandoning his post as military engineer in charge of the city's fortifications. A letter from Michelangelo to his friend Battista della Palla on the 25th of September 1529 makes clear his reasons:
Battista, dearest friend, I left Florence, as I think you know, meaning to go to France. When I reached Venice, I inquired about the road, and they told me I should have pass through German territory, and that he journey is both perilous and difficult. Therefore I thought it well to ask you, at your pleasure, whether you are still inclined to go, and to beg you; and so I entreat you, let me know, and say where you want me to wait for you, and we will travel together. I left home without speaking to any of my friends, and in great confusion. You know that I wanted in any case to go to France, and often asked for leave, but did not get it. Nevertheless I was quite resolved, and without any sort of fear, to see the end of the war out first. But on Tuesday morning, September 21, a certain person came out by the gate at S. Niccolo, where I was attending to the bastions, and whispered in my ear that, if I meant to save my life, I must not stay at Florence. He accompanied me home, dined there, brought me horses, and never left my side till he got me outside the city, declaring that this was my salvation. Whether God or the devil was the man, I do not know.
Symonds, John Addington: "The Life of Michelangelo Buonarroti", Modern Library (New York), p.267-8