Of a population estimated at 80,000 before the Black Death of 1349, about 25,000 are estimated to have been engaged in the city's wool industry. In 1345, Florence was the scene of an attempted strike by wool carders ("ciompi"), who in 1378 rose up in a brief revolt against oligarchic rule known as the Revolt of the Ciompi. After their suppression, the city came under the sway of the Albizzi family, bitter rivals of the Medici family, between 1382 and 1434. Cosimo de' Medici (1389–1464) was the first Medici family member to govern the city from behind the scenes. Although the city was technically a democracy of sorts, his power came from a vast network of patronage and a political alliance to new immigrants to the city, the "gente nuova". The fact that the Medici were bankers to the pope also contributed to their prominence. Cosimo was succeeded by his son Piero di Cosimo de' Medici (1416–1469), who was shortly thereafter succeeded by Cosimo's grandson, Lorenzo in 1469. Lorenzo de' Medici was a great patron of the arts who commissioned works by Michelangelo, Leonardo da Vinci and Sandro Botticelli.