 In order to get to Bihać, Đurišić made a safe-conduct agreement with elements of the Armed Forces of the Independent State of Croatia (HOS) and with the Montenegrin separatist Sekula Drljević. The details of the agreement are not known, but it appears Đurišić, Ostojić and Baćović and their troops were meant to cross the Sava river into Slavonia where they would be aligned with Drljević as the "Montenegrin National Army" with Đurišić retaining operational command. The Chetniks however, appear to have tried to outsmart the HOS forces and Drljević by sending their sick and wounded across the river, but retaining their fit troops south of the river, after which they began moving them westwards. Harassed by both the HOS troops and Partisans, they reached the Vrbas river, which they began to cross. In the Battle of Lijevče Field, north of Banja Luka, the combined Chetnik force was badly beaten by a strong HOS force which possessed German-supplied tanks.
