Normans, designation for the Northmen, or Norsemen, who conquered Normandy in the 10th cent. and adopted Christianity and the customs and language of France. Abandoning piracy and raiding, they adopted regular commerce and gave much impetus to European trade. They soon lost all connection with their original Scandinavian homeland, but they retained their craving for adventure, expansion, and enrichment. In 1066 the Norman Conquest of England made the duke of Normandy king of England as William I (William the Conqueror). The Norman nobility displaced the Anglo-Saxon nobility of England. The Normans readily adapted to the feudalism of N France and are believed either to have introduced feudalism to England or to have strengthened a pre-existing feudal system there.
Early in the 11th cent. bands of Norman adventurers appeared in S Italy, where at first they aided the local nobles in their rebellion against Byzantine rule. A steady stream of land-hungry Norman nobles, under the pretext of expelling the Greeks, proceeded to take over the land. Most remarkable among these adventurers were the numerous sons of Tancred de Hauteville. One of these, William Iron Arm, became lord of Apulia in 1043; he was succeeded by his brother Drogo and by another brother, Humphrey, who defeated (1053) Pope Leo IX when the pope attempted to enforce papal rights in S Italy. In 1059, Humphrey's brother and successor Robert Guiscard was invested by Pope Nicholas II with duchies of Apulia and Calabria and the island of Sicily, which was yet to be conquered. He completed the Norman conquest of S Italy; another brother, Roger I, conquered Sicily, and in 1130 Roger's son, Roger II, set up the kingdom of Sicily, which included the island and the Norman possessions in S Italy.
The Normans soon adopted Italian speech and customs. Their ambitious plans against the Byzantine Empire were a factor in bringing about the Crusades, in which they at first played an important part. The medieval Normans were notable for the great authority given their dukes; for their enthusiasm for conquest; and for their economic and social penetration of conquered areas. Wherever the Normans went, Norman architecture left its traces.
See E. Curtis, Roger of Sicily and the Normans in Lower Italy (1912); C. H. Haskins, The Normans in European History (1915, repr. 1966) and Norman Institutions (1918, repr. 1960); J. J. C. Norwich, The Normans in the South, 1016–1130 (1967) and The Kingdom in the Sun, 1130–1194 (1970); E. Searle, Predatory Kinship and the Creation of Norman Power (1988).