The preaching of the First Crusade certainly presented Bohemond with a unique opportunity to escape the relentless pressure put on him by his half-brother Roger, who was acting in his own interests as the legitimate heir of Robert Guiscard and had the protection of his uncle Roger of Sicily, who intervened several times in favour of his namesake nephew. Ever since the death of their father in Cephalonia in 1085, the two half-brothers had been locked in an almost continuous civil strife for five years, which saw the emergence of Bohemond as a significant landowner in Apulia and Calabria.

Whether or not Bohemond had possessions of his own before 1085 from which he could draw troops is impossible to say. A rebellion, however, mounted against Roger immediately after receiving news of his father's death, with the aid of Jordan of Capua and other magnates, was a complete success for Bohemond; Roger had to cede to him the important cities of Oria, Taranto, Otranto, Gallipoli and the lands of his cousin Geoffrey of Conversano, which included Conversano, Montepeloso, Polignano, Monopoli and Brindisi.