Florence was at this time a Republic, but the city was increasingly under the influence of a single powerful family, the Medici, led by Lorenzo de' Medici, who came to be known as "Lorenzo the Magnificent". In 1481 Leonardo commenced an important commission, the painting of a large altarpiece for the church of San Donato in Scopeto. The work was never completed. Leonardo left Florence and travelled to Milan carrying a gift from Lorenzo to the regent ruler, Ludovico Sforza. He was employed by Ludovico from 1481 to 1499, during which time his most important works were the "Virgin of the Rocks", the "Last Supper" and a huge model of a horse for an equestrian monument which was never completed. Other important events during this time were the arrival in his studio of the boy Salaì in 1490, and in 1491 the marriage of Ludovico Sforza to Beatrice d'Este, for which he organized the celebrations. When Milan was invaded by the French in 1499, Leonardo left and spent some time in Venice, and possibly Rome and Naples before returning to Florence.