and in 1158, the Byzantines left Italy. Unlike the Norman conquest of England (1066), which took place over the course of a few years after one decisive battle, the conquest of Southern Italy was the product of decades and many battles, few decisive. Many territories were conquered independently, and only later were all unified into one state. Compared to the conquest of England, it was unplanned and unorganised, but just as permanent. Thanks to the marriage between the Emperor Henry VI and Constance, heiress to the Sicilian throne, the Kingdom of Sicily was in a personal union with the Holy Roman Empire from 1194 to 1254. The Kingdom of Sicily would last under various dynasties until the 19th century. Late Middle Ages and Renaissance (14th century to 1559) In the 14th century, Northern Italy and upper-central Italy were divided into a number of warring city-states, the most powerful being Milan, Florence, Pisa, Siena, Genoa, Ferrara, Mantua, Verona, and Venice. High Medieval Northern Italy was further divided by the long running battle for supremacy between the forces of the papacy and of the Holy Roman Empire. Each city aligned itself with one faction or the other, yet was divided internally between the two warring parties, Guelfs and Ghibellines. The county of Savoy expanded its territory into the peninsula in the late Middle Ages, while Florence developed into a highly organized commercial and financial city-state, becoming for many centuries the European capital of silk, wool, banking and jewelry. Warfare between the states was common, invasion from outside Italy confined to intermittent sorties of Holy Roman Emperors. Renaissance politics developed from this background. Since the 13th century, as armies became primarily composed of mercenaries, prosperous city-states could field considerable forces, despite their low populations. In the course of the 15th century, the most powerful city-states annexed their smaller neighbors. Florence took Pisa in 1406, Venice captured Padua and Verona, while the Duchy of Milan annexed a number of nearby areas including Pavia and Parma. The Duchy of Milan found itself in the focus of European power politics in the 15th century, leading to the drawn-out Italian Wars, which persisted for the best part of the 16th century before giving way to the Early Modern period in Italy. In the 14th century, Italy presents itself as divided between the Kingdom of Naples and Sicily in the south, the Papal States in Central Italy, and