The Venetians were paid for aid: they defeated Bohemond & were rewarded

Summary:
Alexios I was informed by Georgios Palaiologos of the massive size of the force attacking Dyrrachium, and realised the problem he faced. Thus he communicated with Sulayman of Nicaea and with the Venetians to enrol them as allies. Using promises and gifts he called upon the Venetians for aid against Robert. They equipped a large expedition, paid for by privileges enshrined in chrysobulls. Arriving at Pallia, the Venetians first shrank from fighting the well-armed Norman fleet. Robert sent his son Bohemond to make the Venetians acclaim Michael VII and Robert himself. Next day they refused to do this and made fun of Bohemond's beard. He attacked them as they were in the "sea harbour" formation, but after a hard fight he was defeated and pursued back to his camp. The Venetians then sent ambassadors to Alexios, who rewarded their doge Domenico Silvo. Later they were given a small quarter in Constantinople 
Dates:
1081 Summer 
Emperor Alexios I Komnenos (Alexios 1)
  • Arriving at Pallia, the Venetians first shrank from fighting the well-armed Norman fleet, but later they defeated Bohemond 61; they then sent ambassadors to Alexios, who rewarded the doge of Venice (Domenico 15001) (:) Anna Komnene 123.12-124.37
  • Had been helped by the Venetians against Robert 61 Guiscard, when he crossed from Italy to invade Dyrrachion; in return he gave them the Embolon, a narrow quarter in Constantinople, and unique freedom from taxation (:) ῎Εμβολον Kinnamos 280.25-281.5
  • He was informed by Georgios 61 of the massive size of the attack on Dyrrachium, and realised the problems he faced; he communicated with Sulayman 5000 and with the Venetians to enrol them as allies (:) Anna Komnene 122.65-81
  • Using promises and gifts he called upon the Venetians for aid against Robert 61; they equipped a large expedition, paid for by privileges enshrined in chrysobulls (:) Anna Komnene 122.76-81
Bohemond of Taranto (Bohemond 61)
  • The Venetians refused to acclaim Michael 7 and Robert 61 and made fun of Bohemond's beard; he attacked them as they were in the "sea harbour" formation, but after a hard fight he was defeated and pursued to his camp (:) τὸν λεγὀμενον πελαγολιμένα Anna Komnene 123.12-32
  • Was sent by his father Robert 61 to convert the Venetians at Pallia (Cape Palli) to the cause of the Byzantine pretender (Anonymus 15115, allegedly the emperor Michael VII Doukas) (:) Anna Komnene 123.1-3
  • His beard was mocked by the Venetians who refused to acclaim the (impostor) emperor (Anonymus 15115), so he attacked their ships, largest first (:) Anna Komnene 123.12-16
  • In a sea battle against the Venetians his ship was holed, but he avoided drowning by leaping into another ship (:) Anna Komnene 124.18-23
Domenico Silvio, doge of Venice (Domenico 15001)
  • Was given gifts by Alexios 1 after the victory over the Normans (:) Anna Komnene 124.35-37
Georgios Palaiologos (Georgios 61)
  • When Bohemond 61 was defeated by the Venetians and pursued back to his camp outside Dyrrachion, Palaiologos made a sally and increased the Norman casualties before returning (:) Anna Komnene 124.23-33
Robert Guiscard (Robert 61)
  • When the Venetian fleet arrived near Dyrrachion, he sent Bohemond 61 to make them acclaim Michael 7 and Robert himself; they refused, Bohemond attacked them, but was defeated and pursued back to his camp (:) Anna Komnene 123.1-124.31