The duke’s heart was much grieved by the outrage done to his son-in-law and daughter who had been driven from the imperial throne.  Many felt this to be a grave injury done to the duke, and he wished to take vengeance for it. An old man called Nicephorus had undertaken the reins of government. He was ignorant of war, and although cunning, ingenious and watchful for hidden dangers, he was cowardly and more fearful than to be feared.  He was supported by the commander-in-chief Alexius, a mighty warrior and a man of great astuteness, distinguished both by his courage and by his illustrious ancestry. He had from the first flower of his youth  passed most of his life under arms, and never failed to undertake any enterprise, however difficult, if the holy empire ordered. This general had defeated the empire’s enemies Basiliakos and Bryennius, illustrious Greeks distinguished by their courage and wealth, over both of whom he had been victorious.  Bryennios had fought a pitched battle with him not far from the city [Constantinople], and been defeated and captured. Basiliakos had been defeated by a trick of Alexius. As the two advanced to meet in battle, they pitched camp late in the day very close to each other.  That night the cunning Alexius simulated flight. He abandoned his camp, but without taking all his baggage and leaving some of the tents standing.  Next morning the abandoned baggage and tents, and some horses left behind, made it seem that he was in flight. Seeing nobody arrayed for battle against him and the camp unpeopled,  Basiliakos sent out his men to scout around and report back to him if they found any noise from horses or men. But no voices from troops talking, no sound or neighing of horses could be heard. Basiliakos thought that everything was safe and believed that his enemy had been terrified by his forces and fled. He dined and fell into a drunken sleep, and his whole army lay quietly in their camp. Alexius arrived secretly and fell upon his enemies who were terror-stricken.  Since they were [also] hindered by the darkness of the night, nowhere appeared safe to them and they had no hope of flight. They were captured and killed. Sleep and over-indulgence in wine made them slothful, and they were unable either to run away or stand to arms. Basiliakos was blinded and sent to you, Nicephorus, against whose rule he had dared to rebel, to see him who was now unable to see.  So Alexius was, through his energy and cunning, victorious over the empire’s many enemies either through force of arms or by trickery.
Wishing to cross the sea, the duke instructed weapons to be made ready and ordered his soldiers to muster at Otranto.  He had ships built, while he himself stayed at Salerno, levying contributions everywhere and unceasingly sending on recruits. He requested his trusted troops to come with him on the ships that had been prepared. It seemed to many that this expedition was an unfair and burdensome matter, and in particular those who had wives and much-loved children at home were reluctant to fight such a war.  But the duke reinforced his gentle persuasions with threats and compelled many to go. All mustered as he ordered at Otranto. The duke chose transport vessels from Dalmatia, which the people there had, on his request, sent to assist him.  He filled these with arms, horses, supplies and men, and despatched them to Corfu, an island not far from the city of Otranto. The journey was speedy thanks to favourable winds. The duke’s knights disembarked on the island  and made a ferocious attack, striking fear into all who lived there.
At the same time the old man mentioned earlier was driven from the imperial throne. The gallant Alexius, who had so strengthened the empire and secured so many victories over its enemies,  drove him out, furious over the injury which had been done to his brother. Accompanied by all the imperial forces and finding the City ungarrisoned, he had an easy task in overcoming the old man who was forced to become a monk.  For three days the general allowed the invaders to plunder the City. The fierce Persians dared to violate holy places with their impious hands (Alexius had brought them to the City that he might be the more feared). Once he had seized the government of the empire by force of arms, this sophisticated soldier showed  no little honour to Robert’s daughter, for he had heard that the duke wanted to come there and he strove to pacify him and to turn his mind away from such schemes. But the duke was sternly resolved and refused to abandon his plan.
 He remained for some time at Otranto awaiting the arrival of his wife and of many of the counts whom he expected to accompany him on the forthcoming expedition. An imposter claiming to be Michael had arrived claiming to have been unjustly deprived of the imperial power and tearfully lamenting his flight  The duke received the wretched man and treated him honourably, showing him favour and kindly respect. The credulous populace rushed to him and bowed to him in greeting.  The duke welcomed this associate and took him with him when he set off, the better to justify his expedition.
A little while before his crossing he received messages from that king whom the pope had declared deprived of his kingdom, requesting him to assist him against the pope and those proud citizens  who had unreasonably rebelled against him (for the king had at this time come to besiege Rome). Although the duke gave a kindly and favourable reply, the envoys returned without any concrete result. He made known to Pope Gregory, whose sincere supporter  he was, all the messages of the excommunicated king. He assured him that he would never have set this expedition in motion if he had foreseen the enemy’s attack, but he said that since the preparations were now so far advanced it would be impossible to abandon the enterprise.
 An alliance with Guiscard, both matrimonially and politically, was sought after, as much by the German Emperor as the Byzantine emperor. Emperor Michael VII had suggested a military alliance and the marriage of the Emperor’s brother to Guiscard’s daughter Helen and also bestowed high Byzantine honours on Guiscard’s family. Taking advantage of a period of political anarchy and troubles in Byzantium, which had lasted since 1076, Guiscard, ostensibly seeking to restore Michael VII, who had been overthrown in favour of Nicephorous Botaniates in 1078, and with his daughter confined to a convent, decided to attack Byzantium. To guarantee Apulia against attack from the new rulers of Byzantium, Robert wanted the territories on the Adriatic coast of the Balkan Peninsula, and he began to build a large navy.
 Nicephorus III Botaniates, who was in his sixties was Byzantine emperor from 1078 to 1081 and belonged to a family which claimed descent from the Roman Fabii; he rose to be commander of the troops in Asia. In 1078, he revolted against Michael VII, and with the connivance of the Seljuk Turks marched upon Nicaea, where he made himself emperor. In the face of another rebellious general, Nicephorus Bryennius, his election was ratified by the aristocracy and clergy. With the help of Alexius Comnenus, he drove Bryennius and other rivals out of the field, but failed to clear the invading Turks out of Asia Minor. Nicephorus ultimately quarreled with Alexius, who used his influence with the army to depose the emperor and banish him to a monastery. In the years of his reign Nicephorus had entirely given himself over to debauchery.
 Basiliakos and Bryennius, successively dukes of Dyrrachion were both pretenders to the throne. Alexis defeated and took Nicephorus Bryennius prisoner in Thrace. After his defeat, Basiliakos took refuge in Thessalonica but he was delivered by its citizens to Nicephorus Botiantes who had him blinded.
 Crisis within the Byzantine Empire in the late 1070s enabled Robert Guiscard to undertake an audacious enterprise against a weakened state. In 1081 he, assisted by his son Bohemond crossed the Adriatic Sea with a considerable navy and invaded mainland Greece. The first campaign in 1081-1082 saw a series of victories on the Dalmatian coast and in Macedonia. The Norman leaders benefited from papal support for their success at Durazzo in 1081 whereas at Hastings in 1066 they had the papal banner: William I received his from Pope Alexander II and Robert Guiscard from Pope Gregory VII. Initially, he had some success but a combination of Norman revolts in Apulia and Alexius Comnenus becoming emperor in 1081 compelled him to return to Italy to reassert his authority in April 1082.
 The Ragusians and Dalmatians who played an important role in the naval fighting at Durazzo were subjects of King Demetr Zvonimir, king of Croatia and Dalmatia. Whether there was a formal alliance between Demetr Zvonimir and Guiscard is a matter of some debate though Croatian historians maintain that there was. The inhabitants of Ragusa sent two galleys and those of Spalato one.
 Malaterra stated that a vanguard of fifteen ships landed on Corfu while Bohemond took Valona, Iericho and Kanina.
 Nicephorus Botaniates was dethroned by Alexius Comnenus in April 1081.
 Constantine Ducas, son of Michael VII and Mary of Alanie, the adoptive mother of Alexius Comnenus who Nicephorus Botiantes had disinherited. Alexius was the lover of the Empress Maria Bagrationi, a daughter of king Bagrat IV of Georgia who was successively married to Michael VII Ducas and his successor Botaniates and was renowned for her beauty. Alexius and Maria lived almost openly together at the Palace of Mangana, and Alexius had Michael VII and Maria’s young son, the prince Constantine Ducas, adopted and proclaimed heir to the throne. The affair conferred to Alexius a degree of dynastic legitimacy, but soon his mother Anna Dalassena consolidated the Ducas family connection by arranging the Emperor’s wedding with Irene Ducaena or Doukaina, granddaughter of the caesar John Ducas, head of a powerful family and the ‘kingmaker’ behind Michael VII. Alexius’ involvement with Maria continued and shortly after his daughter Anna Comnena was born, she was betrothed to Constantine Ducas and moved to live at the Mangana Palace with him and Maria. The situation however changed drastically when John II Comnenus was born: Anna’s engagement to Constantine was dissolved, she was moved to the main Palace to live with her mother and grandmother, Constantine’s status as heir was terminated and Alexius became estranged with Maria, now stripped of her imperial title. Shortly afterwards, the teenager Constantine died and Maria was confined to a convent.
 These were the Turkish mercenaries in the army of Alexius Comnenus.
 Gregory VII announced the arrival of Michael VII to Italy to the bishops of Apulia and Calabria on 25th July 1080 who sought the support of the Holy See and the Normans to restore him to the imperial throne. Most of the contemporary sources recognised him as an imposter though the Lupus Protospatharius and the Annals of Bari saw him as emperor. Anna Comnena recounts two stories about him: either that he was a monk named Rector who passed himself off as Michael or that Guiscard set up an imposter to justify his war.
 Henry IV began his siege of Rome on 21st May 1081. Interestingly, Guiscard’s response to the imperial embassy was oral but he wrote to Gregory VII.