During this time John also reorganized the Byzantine army, making it into a professional fighting force, and not the hodge podge of local forces it had been previously. He created permanent, fortified military camps in both Anatolia and the Balkans, where his field armies could be concentrated and trained, and added a large cavalry component to the army (most famously the Kataphraktoi of Macedonia) which allowed the Byzantines to effectively fight the more mobile Turks. Yet John died suddenly in 1143, possibly from a poison arrow treacherously sent to him by jealous crusaders who did not want him to succeed and encroach on their territory or sovereignty. His sudden death kept the Byzantines from continuing their conquests of Anatolia, and historian Zoe Oldenbourg believes that, if John had lived but a few more years, much larger territorial gains would have been made by the Byzantines.