 Chetnik ideology was influenced by the memorandum of the Serbian Academy of Sciences and Arts.On 28 June 1989, the 600th anniversary of the Battle of Kosovo, Serbs in north Dalmatia, Knin, Obrovac, and Benkovac where there were "old Chetnik strongholds", held the first anti-Croatian government demonstrations.On the same day, Momčilo Đujić declared Vojislav Šešelj "at once assumes the role of a Chetnik vojvoda" and ordered him "to expel all Croats, Albanians, and other foreign elements from holy Serbian soil", stating he would return only when Serbia was cleansed of "the last Jew, Albanian, and Croat".