'Ristow' was a German and Croat operation against the partisan forces of Marshal Josip Broz Tito in the area between Bosanski Novi and Prijedor within the puppet state of Croatia in occupied Yugoslavia (24/28 December 1943).
The operation’s objective was the clearing and securing of the area parallel with and to the south of the railway line linking Bosanski Novi and Prijedor in western Bosnia, where a build-up of the partisans' 7th 'Banija' Division had been reported.
The German contribution to the operation was the 383rd Grenadierregiment, 373rd Aufklärungsabteilung and 1/373rd Artillerieregiment of Generalleutnant Emil Zellner’s 373rd Division (kroatische), and three armoured vehicles of the 202nd Panzerabteilung, while that of the Croats was the 11th Mountain Regiment of General Mirko Gregurić's 3rd Mountain Brigade.
The advance of the German and Croat forces started to encounter increasingly determined partisan resistance on 25 December, and this continued to the end of the operation three days later. As a result of the unexpectedly heavy fighting and the many casualties they suffered, the comparatively small German and Croat forces failed to clear the assigned area, and the operation was considered a failure. The Germans admitted the loss of nine men killed and 18 wounded, together with Croat losses of 13 men killed, 51 severely wounded, a large number of lightly wounded, and 13 missing. The partisan losses are unknown, but local eyewitnesses reported the burying of 75 partisan dead in just one location, so in overall terms the partisan casualties are believed to have been high.