The Roman Invasion of Sinope was a military conflict fought in 1409 between the forces of the Roman Empire and the Empire of Trebizond against the forces of the Turkish Isfendiyarid Emirate of Sinope. By the start of the war, the two Greek states had reconciled their previous differences through political marriage between John VIII and Alexios Megas Komnenos' daughter. Alexios was also given a prominent political position within the Roman Empire to further sweeten the deal. With the two forces unified, the allies decided to test their strength and expand their influence in the Black Sea area by targeting the weakest state they could find, the Emirate of Sinope.