Robert Guiscard was one of several brothers who came to Italy from Normandy to work as mercenaries and gain their fortune. After arriving in Italy in 1046, he served in several campaigns before taking the place of his brother Humphrey as Duke of the Normans. His power steadily grew, as he became involved in the politics of both Italy and the Byzantine empire. His most famous victory came at the battle of Durazzo on October 1081 (in the text below, the battle is dated to 1082 at a place called Durres) where he defeated a Byzantine army. Robert Guiscard went to become the duke of Apulia and Calabria, and founded the Kingdom of the Two Sicily’s. For more information on Robert Guiscard, please see this biography of him, and Rupert Willoughby’s article, The Shock of the New (innovative lance charge leads to Norman victories) from History Today v.49 (1999).
Annales Lupi Protospatharii was written in the city of Bari while it was capital of the Byzantine territories in Italy, and during the first few decades of the Norman domination (ca. 850 – ca. 1100). Along with the Annales barenses and the Anonymi barensis chronicon, this work has long been recognized as among the most important historical sources for the place and period. The Annales Lupi Protospatharii covers the period from 855 to 1102. Only those paragraphs related to Robert Guiscard’s career are included below.
Paragraph 159 –  – And Humphrey died, and his brother Robert [Guiscard] became duke [of the Normans].
Paragraph 165 – The year 1061, the fourteenth indiction. This year Duke Robert captured the city of Acrenza.
Paragraph 167 – And in this year  Duke Robert entered the city of Oria. And again, he took the city of Brindisi and the merarches.
Paragraph 170 – The year 1065, the third indiction. This year Duke Robert invaded Sicily, and killed a multitude of Agarenes; and he took a hostage from the city of Palermo.
Paragraph 175 – The year 1068, the sixth indiction. This year, on 16 February, Duke Robert besieged the city of Irsina, and since he was accomplishing nothing there, he went off with a few men to Uggiano, and took it. And through the treachery of a certian Goffredo, the Duke entered the aforementioned city of Irsina.
Paragraph 176 – The year 1069, the seventh indiction. This year, in the month of September, the aforementioned Duke Robert laid siege to the city of Bari.
Paragraph 178 – The year 1070, the ninth indiction. This year in the month of January there was a great slaughter in the city of Brindisi; for while the Normans wanted to capture it, forty of them were captured, along with forty-three others, their sergeants; and the heads of all these men were sent off to the [Byzantine] Emperor.
Paragraph 179 – The year 1071, the ninth indiction. This year Duke Robert entered Brindisi, after leaving the siege of Bari; for the Duke had had a causeway built, with which to close the port of the aforementioned city of Bari.
Paragraph 180 – And in this year, Bisanzio Guideliku was assassinated in Bari through the treachery of a certain Argirizzo, the son of Giannazzo.
Paragraph 181 – And on 15 April Duke Robert took the city of Bari.
Paragraph 182 – And in the month of July the aforementioned Duke crossed the Adriatic sea, and arrived in Sicily with fifty-eight ships.
Paragraph 183 – The year 1072, the tenth indiction. This year on 10 January Duke Robert entered Palermo, a city in Sicily.
Paragraph 185 – The year 1076, the fourteenth indiction. This year a certain nephew [grandson?] of the King of Africa was captured by Roger, Duke Robert’s brother, who was in charge of Sicily, with a hundred and fifty ships in the city of Mazara.
Paragraph 187 – The year 1077, fifteenth indiction. This year the city of Salerno was besieged by Robert [Guiscard], the Duke of the Normans, and taken by him.
Paragraph 189 – And Duke Robert laid siege to Benevento, but his siege was lifted by Radulfo [and?] Count Pepino.
Paragraph 196 – And in this year  the Emperor Michael [VII} arrived in Apulia, seeking help fropm Duke Robert against [Nicephorus III] Botanetiates.
Paragraph 200 –  And Duke Robert reached Otranto with the aforementioned Emperor Michael. He sent ahead ships to the island of Corfu, and they captured it; and he went there himself after a short time, along with the Emperor. And in the month of July they laid siege to Durres, both by land and by sea; but the Venetian fleet came and broke the blockade, and opened the sea to the inhabitants of Durres.
Paragraph 201 – This year [Nicephorus III] Botaneiates was made a monk and Alexius [I Comnenus] was made emperor.
Paragraph 204 – And in this year  Emperor Alexius gathered a large army and began a battle with Duke Robert not far from Durres, and he was forced to turn and flee. More than 6000 of his men fell in that battle; there had been more than 70,000 men in his army. And in the month of January Duke Robert took the city of Durres through the treachery of a few of the Venetians.
Paragraph 205 – And at this time the aforementioned King Henry [IV] laid siege to Rome, in order to enter it by force and to make the Archbishop of Ravenna Pope, but he was unable to do it. But Duke Robert returned from Durres, leaving his son Bohemund in charge there, and brought help to Pope Gregory, when the King was already tarrying in the region of Liburia [Tuscan coast] to make war on the province of Matilda [Countess of Tuscany], who was of Pope Gregory’s party.
Paragraph 209 – And at this time  the people of Rome, deserting their allegiance to Pope Gregory VII, sent amabassadors to the aforementioned king [Henry IV], to get him to come to Rome. But the duke anticipated this, and sent more than thirty thousand gold pieces to the Romans, to reconcile them to himself and to the Pope; and this is what happened.
Paragraph 210 – The King came, nonetheless, and took all the region of Trastevere, in which rises the temple of the Prince of the Apostles. And in the month of June, he left his garrison and his son in a castle which he had built there to fight against Pope Gregory, who was confining himself to the Lateran and the Celian hill; he took forty hostages from Rome, and withdrew to the region of Tuscany.
Paragraph 211 – And in the month of May the Duke laid siege to Canne, a city in Apulia, and took it in the month of June.
Paragraph 212 – The year 1084, the seventh indiction. This year Duke Robert gathered a multitude of Normans and Longobardi and other peoples, and went to Rome to liberate Pope Gregory, who was being kept under close siege; and this was accomplished. For the Duke captured most of the city on coming to Rome, manfully rescued the Pope from it, and escorted him to Salerno.
Paragraph 213 – The year 1085, the eight indiction. This year the aforementioned Duke came to Brindisi with a huge naval detachment and an innumerable army of men. And after arranging there his naval strategy, he entered the Adriatic sea, and came to an island called Cassiope, where the Venetian fleet – and the son of the Doge – with many ships was hostile to Duke Robert.
Paragraph 214 – But when a sea battle took place between them, the Normans had the victory. In the battle, more than five thousand men were killed; and besides that, five ships were captured, and two were sunk with all hands, so that those who were able to avoid the sword of the warrior were swallowed up in the depths of the sea.
Paragraph 216 – In the month of July, while the said Duke was staying in the place which is called Vonitsa, after the Venetians had been defeated, and while his army was stationed in Cephalonia in order to take a certain city, while he himself was residing in the said place with a part of his army, preparing to go by sea with a large naval force and an innumerable multitude of soldiers to the Royal City [Constantinople], by the command of God, almighty and most merciful, who reproves and brings to naught the thoughts and plans of princes which do not proceed from his own, the Duke died of flux.
This translation is from The Annales Barenses and the Annales Lupi Protospatharii: Critical Edition and Commentary, by William Joseph Churchill (University of Toronto PhD dissertation, 1979).