Emperor Basil II enlists Venetian help in protecting the Dalmatian coast and Adriatic waters from Bulgarian aggression.

Robert Guiscard, Duke of Apulia and Calabria, has spent the majority of his reign consolidating Norman power along the heel and toe of Italy by expelling Constantinople’s armies.

Guiscard has been pushing north toward the Papal States (to which the Duchy of Apulia and Calabria is allied) and threatening imperial control of cities along the Ionian and Adriatic seas.

Following the Norman conquest of the Catepanate of Italy and Saracen Sicily, the emperor in Constantinople, Michael VII Doukas, had betrothed his son to Robert Guiscard's daughter.

When Michael is deposed, Robert takes this as an excuse to invade the Empire.

Guiscard leads his army and navy across the sea in May 1081 to lay siege to the port city of Durazzo, as it is one end of the famous Via Egnatia, a direct route to the imperial capital of Constantinople.

At Avlona, south of Durazzo, captured earlier in the year by Bohémond, son of Robert Guiscard and his Norman first wife, Alberada, the Norman fleet is joined by a few Ragusan vessels and …

Bohemond in 1105 had been in Bari to enlist reinforcements for his struggle with the Empire.

In September of that year, Bohémond had gone to Rome to interview Pope Paschal II, and had succeeded in winning him over to the idea of a new Crusade.

Whatever the original intention, there will result not an expedition against Muslims but a planned attack on the imperial city of Dyrrhachium.

It is a matter of historical debate how far Bohemond’s 'crusade' to be directed against Constantinople has been to gain the backing and indulgences of Pope Paschal II.

Either way, he had enthralled audiences across France with gifts of relics from the Holy Land and tales of heroism while fighting the infidel, gathering a large army in the process.

Henry I of England had famously prevented him from landing on English shores, so great was his pull expected to be on the English nobility.

Bohémond had journeyed early in 1106 through France, where babies are named for him, crowds hear him denounce the perfidious Emperor Alexios, and shrines receive sacred relics from his hands.

His newfound status has won him the hand of Constance, the daughter of the French king, Philip I, who he marries in the spring.

Of this marriage writes Abbot Suger:

Bohemond came to France to seek by any means he could the hand of the Lord Louis' sister Constance, a young lady of excellent breeding, elegant appearance and beautiful face.

So great was the reputation for valor of the French kingdom and of the Lord Louis that even the Saracens were terrified by the prospect of that marriage.

She was not engaged since she had broken off her agreement to wed Hugh, count of Troyes, and wished to avoid another unsuitable match.

The prince of Antioch was experienced and rich both in gifts and promises; he fully deserved the marriage, which was celebrated with great pomp by the bishop of Chartres in the presence of the king, the Lord Louis, and many archbishops, bishops and noblemen of the realm."

Dazzled by his success, Bohemond has resolved to use his army of thirty-four thousand men, not to defend Antioch against the Greeks, but to attack Alexios.

A landless young man thirty years earlier, he now stands at the pinnacle of his career.

He is ready to launch his private crusade against Constantinople by September 1107; within the month, he has landed a large army at Avlona, with which he lays siege to Dyrrhachium.