The unpredictable behaviour of George Monomachatos increased Guiscard's enthusiasm for the attack. When he heard of the arrival of Georgios Palaiologos at Dyrrachion, Robert immediately fitted out his fleet with towers suitable for capturing cities and covered them with defensive hides, his final preparations for the expedition. He set sail for Dyrrachion in strict formation, hoping to capture it quickly by surrounding it with siege machines both on land and sea, which would prepare the way for a violent assault. But as he passed Kerkyra, at a headland called Glossa, he was struck by a terrible and ominous summer storm, which sank many of his ships and drove others on to the rocks; the siege-towers and heavy defensive skins made the ships less sea-worthy. His losses in the storm did not deter him from his purpose. He stayed for a week at Glabinitza to recover and wait for his last forces to arrive, before reaching Dyrrachion with Bohemond. The army assembled outside the city by June 17. His army and fleet continued to increase in size, and neighbouring towns were captured and laid waste. An anonymous Latin envoy from the archbishop of Bari to Guiscard was the source of Anna Komnene for this part of her history