This was a German and possibly Croat operation against the partisan forces of Marshal Josip Broz Tito in the valley of the Vrbas river of the puppet state of Croatia in occupied Yugoslavia (4/9 January 1944).
The undertaking’s objective was to open the Vrbas river valley and roads paralleling it by driving south from Banja Luka to Mrkonjić-Grad and Jajce.
The partisan forces involved were the 1st Proletarian Assault Division, 6th Division and 11th Assault Division, while the Axis forces were elements of Generalleutnant Walter Stettner Ritter von Grabenhofen’s 1st Gebirgsdivision and Generalleutnant Eduard Aldrian’s 373rd Division (kroatisch), the 901st Panzergrenadier-Lehr-Regiment, the 92nd Grenadierregiment, and possibly a small contribution of Croat elements.
The operation was part of the larger ‘Waldrausch’, and the German forces converged on Jajce from the north, east and west, taking the town on 9 January on the fourth occasion Jajce had changed hands in 15 months. The German lines of communication between Banja Luka to Jajce were thus reopened, at least for a time. The number of casualties are no longer known, but were probably no more than several hundred on each side.