With the occupation of southeastern Carinthia by Yugoslav troops, the confrontation evolved into armed clashes. The provisional Carinthian government under Governor Arthur Lemisch decided to take up arms to preserve the southern Carinthian border on the Karawanks range. The bitter fighting of paramilitary groups around Arnoldstein and Ferlach alarmed the Entente powers. They arbitrated a ceasefire, whereafter a nine-day U.S. Army commission under Lt.Col. Sherman Miles scouted the disputed region in January and February 1919 and made the crucial recommendation that the Karawanks frontier should be retained, thus opening the possibility of a plebiscite. Yugoslav representatives urged for a border on the Drava; American delegates however spoke in favor of preserving the unity of the Klagenfurt Basin and convinced the British and French delegations. Until May 7, all occupied Carinthian territories were vacated. When Yugoslav forces under General Rudolf Maister made an attempt to re-enter the region on 28 May 1919, they were forced to withdraw by the Entente authorities.