When Mahmud II ordered his forces to advance on the Syrian frontier, Ibrahim attacked and destroyed them at the Battle of Nezib (24 June 1839) near Urfa. In an echo of the Battle of Konya, Constantinople was again left vulnerable to Ali's forces. A further blow to the Ottomans was the defection of their fleet to Muhammad Ali. Mahmud II died almost immediately after the battle took place and was succeeded by sixteen-year-old Abdülmecid. At this point, Ali and Ibrahim began to argue about which course to follow; Ibrahim favoured conquering the Ottoman capital and demanding the imperial seat while Muhammad Ali was inclined simply to demand numerous concessions of territory and political autonomy for himself and his family.