Passage: Robert's son Bohemond and his brother Roger of Sicily attacked Amalfi in 1097, but were repulsed. During this siege, the Normans began to be drawn by the First Crusade. Marinus was defeated after Amalfitan noblemen defected to the Norman side and betrayed him in 1101. Amalfi revolted again in 1130, when Roger II of Sicily demanded its loyalty. It was finally subdued in 1131 when Admiral John marched on it by land and George of Antioch blockaded it by sea, establishing a base on Capri.

Question: Who betrayed Marinus?
Amalfitan noblemen