Book II covers the period between 1043 and 1068. William of Apulia made constant use of now lost annals from the region of Bari. An important theme of this book is the attempts by the Byzantine government to neutralise the Norman threat. Initially, Constantine Monomarkos tried tentatively to hire the Normans as mercenaries to fight against the Turks in Asia Minor. In this process, Argyrus played a key, if unsuccessful role. Argyrus also acted as intermediary between the emperor and pope Leo IX in the events leading up to the battle of Civitate. William of Apulia is the only chronicler who knew of Argyros’ exile (II: 275-280) though he believed this was immediately after and a consequence of the defeat of the Byzantine-papal alliance at Civitate while Argyrus continued to have a major political role until at least 1058. His account of Civitate contained the most complete list of those involved on both sides (II: 131-135).
His account of the conquest of Calabria by Robert Guiscard is brief, fragmentary and sometimes legendary and he does not mention the capture of its capital, Reggio. His narrative makes clear the depradations of the Normans on Calabria and this is confirmed in contemporary Calabrian documents (II: 297-363, 381-383 and 406-15). He provides original information of the rivalry between the families of Amicus and de Hauteville (II: 20-37) and, unlike Amatus or Malaterra of the synod of Melfi 1059 in which he preserved the substance of its lost acts.
The narrative does, however, agree with Amatus and Malaterra on the marriage of Robert to Sikelgaita (II: 426-430) and on the rebellion against Guiscard between 1064 and 1068 (II: 444-478). His long account of the siege of Bari in 1068 (II: 478-573) contained several original details not found in the narrative by Amatus. He is especially useful on the factions that existed inside Bari and which divided the town over how best to deal with the Norman threat and on the attempt to assassinate Guiscard (II: 495-502).