 On the Byzantine side, Theophilos became soon aware of the Caliph's intentions, and set out from Constantinople in early June. His army included the men from the Anatolian and possibly also the European themes, the elite tagmata regiments, as well as a contingent of Persian and Kurdish Khurramites. Under their leader Nasr (converted to Christianity and baptized as Theophobos), these people had fled religious persecution in the Caliphate, deserted to the Empire in the previous years, and formed the so-called "Persian tourma". Setting up camp at Dorylaion, the Emperor divided his forces: a strong corps was sent to reinforce the garrison of Amorion, while he himself set out with the remainder (circa 25,000 according to Haldon and 40,000 according to Treadgold) to interpose himself between the Cilician Gates and Ancyra.
