Duke of Apulia and Calabria, founder of the Norman state of the Two Sicilies; born about 1016; died 17 July, 1085. He was the eldest son of the second marriage of Tancred, seigneur of Haute-ville-la-Guichard near Coutances, Normandy, a fief of ten chevaliers. Already three of his brothers, William Bras-de-Fer and Drogo, about 1034, and Humphrey, about 1045, had entered the pay of the Lombard princes of Southern Italy who were in revolt against the Byzantine Empire. In turn Robert left Normandy accompanied by five horsemen and thirty foot-soldiers, and set out to rejoin his brothers in 1046. Of gigantic stature, broad-shouldered, with blond hair, ruddy complexion, and deep voice, he owed to his crafty shrewdness the soubriquet of "Guiscard" (Wiseacre). He encountered difficulties on his first entrance into Italy. His brother Drogo, who had been elected Count of the Normans, repulsed him. Having wandered about for a time he returned to enter the service of Drogo and assisted him to conquer Calabria. He established himself at the head of a small troop on the heights of San Marco, which dominated the valley of the Crati, whence he practised actual brigandage, surprising the Byzantine posts, pillaging monasteries, and robbing travellers. But subsequent to his marriage with Aubrée, a kinswoman of a Norman chief of the territory of Benevento, he renounced this manner of life and had two hundred horsemen under his command. Drogo having been assassinated in 1051, his brother Humphrey succeeded to his possessions and the title of Count of the Normans, and Guiscard remained in his service. In 1053, he took part in the battle of Civitella, in which Pope Leo IX was vanquished and taken prisoner by the Normans. In 1055, he took possession of Otranto. On the death of Humphrey in 1057, Robert Guiscard caused himself to be elected leader of the Normans to the detriment of the two sons of his brother, whose inheritance he appropriated. At this juncture the Normans aimed openly at taking possession of southern Italy. Richard of Aversa, who had just taken Capua, was after Guiscard the most powerful leader. Through energy of character and skilful policy, Robert Guiscard succeeded in inducing the Norman chiefs to submit to his authority and in accomplishing with them the conquest of Italy. He established his young brother Roger in Calabria in 1058. In 1059, Hildebrand, the chief councillor of Pope Nicholas II, desiring to shield the papacy from the attacks of the adversaries of ecclesiastical reform, entered into an alliance with the Normans. At the Council of Melfi (August, 1059), Guiscard declared himself the vassal of the Holy See, pledged himself to bring about the observance of the decrees of the Council of Lateran with regard to the election of popes, and received in exchange the title of Duke with the investiture of his conquests in Apulia, Calabria, and Sicily. He at once began to make war on the remaining Byzantine possessions, took possession of Reggio (1060), despatched his brother Roger to begin the conquest of Sicily, took Brindisi (1002), and finally, in 1068, laid siege to Bari, the capital of Byzantine Italy, which he entered after a siege of three years on 16 April, 1071. In the following year, the capture of Palermo, besieged at once by Robert and Roger, left the Normans masters of all Sicily. Roger retained the greater part of the country, but remained his brother's vassal.

These conquests would have been but of ephemeral duration had Guiscard not devoted all his energy to consolidating them. The Norman chiefs who had become his vassals were not too readily disposed to submit to his authority, and revolted while he was in Sicily. In 1073 Guiscard besieged and reduced to submission all the rebels in succession. The great commercial republic of Amalfi yielded voluntarily to him. At this juncture, however, Gregory VII, alarmed by Guiscard's aggressions on the papal territories excommunicated him. At the same time, Guiscard having wished on the occasion of his daughter's marriage to raise the usual feudal aid, his vassals once more revolted (1078). Having put down this revolt, Guiscard was once again all-powerful, and Gregory VII, threatened by the intrigues of Emperor Henry IV, became reconciled to him (1080). In the interval Salerno had fallen under his sway, and, save for the Norman principality of Capua, which remained independent, and the city of Naples, all southern Italy obeyed him.

Having now reached the height of his power, Guiscard conceived the ambition, at the age of sixty-four, to undertake the conquest of the Byzantine empire, whose civilization exercised over him a powerful attraction. As the master of Byzantine Italy, he considered himself the heir of the emperors, caused himself to be depicted on his seal in their costume, and thus inaugurated a tradition which nearly all sovereigns of the Two Sicilies down to Charles of Anjou sought to follow. In May, 1081, Robert and his son Bohemond set out for Otranto, captured the island of Corfu, and disembarked before Durazzo, the possession of which would assure them access to the Via Egnatia, which led through Macedonia to Constantinople. But the emperor Alexius Comnenus had formed an alliance with Venice, whose fleet won a great victory over that of the Normans (July). Alexius came himself to the assistance of Durazzo, but Guiscard, who had burnt his ships in order to inspire courage in his troops, put the imperial army to flight (18 October). Despite this victory, the Normans, being still incapable of laying siege in the regular manner, could not have entered into the place, if Guiscard had not contrived that it should be delivered to him by treason (21 February, 1082). Guiscard was now master of the route to Constantinople, and had advanced as far as Castoria when he received a letter from Gregory VII recalling him to Italy. Henry IV, with whom Alexius Comnenus had formed an alliance, had come down into Italy and was threatening Rome. At his approach the Lombard vassals of Apulia and the Prince of Capua had revolted. Guiscard resigned the command of his expedition to his son Bohemond, who abandoned the march on Constantinople to ravage Thessaly. Guiscard returned to Italy and profited by Henry IV's short delay in Lombardy to subdue his rebellious vassals, capturing their cities one by one (1083). During this time Henry IV returned and laid siege to Rome. On 2 June, 1083, he took possession of the Leonine City, and compelled Gregory VII to seek refuge in the castle of Sant' Angelo. The emperor made his entry into Rome on 21 March, 1084, and, on the following 31 March, he was crowned at St. Peter's by the antipope Clement III. Gregory VII, who all the time was confined to the castle of Sant' Angelo, sent a message to Robert Guiscard. On 24 May, 30,000 Normans camped beneath the walls of Rome. On the 27 May, Guiscard captured the Porta Flaminia, gave battle on the Campo Mania, delivered Gregory VII and installed him in the Lateran while the imperial troops beat a retreat. But the Romans, exasperated by the pillaging of the Normans, revolted. The city was sacked, and the inhabitants massacred or sold as slaves. On the 28 June, Guiscard left Rome and conducted Gregory VII as far as Salerno. Thanks to his intervention the projects of Henry IV had been baffled and the cause of ecclesiastical reform had triumphed.

But Robert Guiscard thought only of resuming his expedition against Constantinople. Beaten by the troops of Alexius Comnenus, Bohemond had been compelled to retire with his army to Italy (1083). Guiscard made fresh preparations, and, at the end of 1084, embarked at Otranto. After having defeated the Venetian fleet, he recovered Corfu and was preparing to capture Cephalonia, where he had just disembarked, when he died after a short illness, 17 July, 1085. Having come into Italy forty years previously as a mere soldier of fortune, he had since founded a sovereign state and become one of the most important personages of Christendom. Two emperors had had to reckon with him. From one of them he had taken Rome, from the other he had been on the point of taking Constantinople. In 1058, he had repudiated Aubrée, the mother of Bohemond, to wed the Lombard Sykelgaite, sister of Gisulf, Prince of Salerno. She gave him three Sons and seven daughters, and appears to have been actively associated in all his undertakings, accompanying him in his expeditions and exercising so much influence over him as to cause him to designate as his successor his son Roger, to the detriment of Bohemond.

Gesta Roberti Wiscardi (Epic in 5 cantos by WILLIAM OF APULIA, composed at the request of Urban II and dedicated to Duke Roger), ed. WILMANS, Mon. Germ. Hist.: Scriptores, IX, 241 sqq.; AMATUS OF MONTE CASINO, Ystoire de li Normant (ed. SOCIÉTÉ DE L'HIST. DE FRANCE, Paris, 1835. Fr. tr. of fourteenth century from orig.); LEO OSTIENSIS (MARSICANUS), Chronica Monasterii Casinensis, ed. WATTENBACH, in Mon. Germ. Hist.: Script., VII, 574 sq.; LUPUS PROTOSPATHARIUS, Annales, 805-1102, ed. in Mon. Germ. Hist.: Script, V, 52 sq.; GEOFFREY MALATERRA, Historia Sicula (to 1099), ed. MURATORI, Rerum italic. Scriptor., V. 574 sqq.; ANNA COMNENA, Alexiade, ed. REIFFERSCHEID (Leipzig, 1884), I-VI; Cecaumeni Strategicon, ed. WASILIEWSKY (St. Petersburg, 1886), 35; GREGORY VII, Registrum epistolarum, ed. JAFFÉ, Bibliotheca rer. germanic., II; CHALANDON, La Diplomatique des Normands de Sicile et de l'Italie méridionaie (Mélanges d'Archéologie et d'Histoire de l'école française de Rome, 1900); HEINEMANN, Normanische Herzogs- und Königsurkunden (Tübingen, 1899); ENGEL, Recherches sur la numismatique et la sigillographie des Normands d'Italie (Paris, 1882); GAY, L'Italie méridionale et l'empire byzantin (Paris, 1904); CHALANDON, Histoire de La domination normande en Italie (Paris, 1907), I, containing excellent bibliography; IDEM, Essai sur le règne d'Alexis I Comnène (Paris, 1900); HEINEMANN, Geschichte der Normannem im Unteritalien und Sicilien (Leipsic, 1894), I; DENTZER, Topographie der Feldzüge Robert Guiscards gegen das byzantinische Reich (Breslau, 1901).

LOUIS BRÉHIER