 The Arabs prepared a massive strike for 737 , however , intended to end the war for good . Marwan apparently went to Damascus in person to persuade Hisham to back this project and was successful : an army 120 @,@ 000 strong was assembled , comprising regular forces of Syria and the Jazira , as well as volunteers for the jihad , Armenian troops under Ashot Bagratuni , and even armed camp followers and servants . The number is clearly an exaggeration , but whatever the real size of Marwan 's army , it was a huge force and certainly the largest ever sent against the Khazars . Marwan first secured his rear by subduing the Armenian factions who were hostile to the Arabs and their client Ashot . He then pushed into Iberia , driving its <unk> ruler to seek refuge in the fortress of <unk> on the Black Sea coast , in the Byzantine protectorate of Abkhazia . Marwan laid siege to <unk> itself , but he was forced to retire due to the outbreak of dysentery among his troops . 
