section_path: Biography/Second Florentine period (1500–1508)
section_name: Second Florentine period (1500–1508)
paragraph_text: Second Florentine period (1500–1508)
  
  When Ludovico Sforza was overthrown by France in 1500, Leonardo fled Milan for Venice, accompanied by his assistant Salaì and friend, the mathematician Luca Pacioli. In Venice, Leonardo was employed as a military architect and engineer, devising methods to defend the city from naval attack. On his return to Florence in 1500, he and his household were guests of the Servite monks at the monastery of Santissima Annunziata and were provided with a workshop where, according to Vasari, Leonardo created the cartoon of The Virgin and Child with Saint Anne and Saint John the Baptist, a work that won such admiration that "men women, young and old" flocked to see it "as if they were going to a solemn festival."
  
  In Cesena in 1502, Leonardo entered the service of Cesare Borgia, the son of Pope Alexander VI, acting as a military architect and engineer and travelling throughout Italy with his patron. Leonardo created a map of Cesare Borgia's stronghold, a town plan of Imola in order to win his patronage. Upon seeing it, Cesare hired Leonardo as his chief military engineer and architect. Later in the year, Leonardo produced another map for his patron, one of Chiana Valley, Tuscany, so as to give his patron a better overlay of the land and greater strategic position. He created this map in conjunction with his other project of constructing a dam from the sea to Florence, in order to allow a supply of water to sustain the canal during all seasons.
  
  Leonardo had left Borgia's service and returned to Florence by early 1503, where he rejoined the Guild of Saint Luke on 18 October of that year. By this same month, Leonardo had begun working on a portrait of Lisa del Giocondo, the model for the Mona Lisa, which he would continue working on until his twilight years. In January 1504, he was part of a committee formed to recommend where Michelangelo's statue of David should be placed. He then spent two years in Florence designing and painting a mural of The Battle of Anghiari for the Signoria, with Michelangelo designing its companion piece, The Battle of Cascina.
  
  In 1506, Leonardo was summoned to Milan by Charles II d'Amboise, the acting French governor of the city. There, Leonardo took on another pupil, Count Francesco Melzi, the son of a Lombard aristocrat, who is considered to have been his favourite student. The Council of Florence wished Leonardo to return promptly to finish The Battle of Anghiari, but he was given leave at the behest of Louis XII, who considered commissioning the artist to make some portraits. Leonardo may have commenced a project for an equestrian figure of d'Amboise; a wax model survives and, if genuine, is the only extant example of Leonardo's sculpture. Leonardo was otherwise free to pursue his scientific interests. Many of Leonardo's most prominent pupils either knew or worked with him in Milan, including Bernardino Luini, Giovanni Antonio Boltraffio, and Marco d'Oggiono. In 1507, Leonardo was in Florence sorting out a dispute with his brothers over the estate of his father, who had died in 1504.