 Complete the following phrase:  The krstaš-barjak crusader flag ; from krst, cross and barjak, flag, banner refers to various war flags with crosses in the centre, part of Serbian tradition, originating from medieval military flags. It is known that Serbian Emperor Stefan Dušan r. 133155 adopted the Byzantine cross flag divellion, which was purple and had a golden cross in the center. According to Serbian epic poetry, during the Ottoman period, hajduks had war flags with crosses krstaš-barjak or icons of saints svetački barjak. The krstaš-barjak is mentioned in poems of the Kosovo Cycle; knight Boško Jugović bears it at the battle of Kosovo 1389. It was used as the general rebel flag during the Serbian Revolution 180417, and as the secondary flag of the supreme commander Karađorđe 180413; Miloš Obrenović 181517. It was adopted as a military flag by the Principality of Montenegro 18521910 and Kingdom of Montenegro 19101918. The Montenegrin war flag used in the 