 The victory of the Guelph party meant the end of Imperial overlordship over northern Italy, and the formation of city-states such as Florence, Venice, Milan, Genoa or Siena.While Venice was turning to the seas, supporting, and acquiring large loot from, the 1204 Fourth Crusade's sack of Constantinople, the other city-states were struggling for control of mainland, Florence being the rising power of the time (annexation of Pisa in 1406).Sicily was invaded in 1266 by Charles I, duke of Anjou; the Angevines were however toppled in the 1282 Sicilian Vespers, and Peter III of Aragon invaded the island.