'Kammerjäger' was an Axis operation to check the arrival of fresh partisan units of Marshal Josip Broz Tito’s forces in the Serb region of German-occupied Yugoslavia (mid-March 1944).
At the start of this period the partisan movement’s 2nd Proletarian Division and 5th Assault Division attempted to enter Serbia from Sandzak with the object of crossing the areas of Ibar and Kopaonik to reach south-eastern Serbia, where they were to join the local partisan forces, the largest and best organised communist units in Serbia, and thus form the basis for increased resistance across the whole of Serbia. Simultaneously the partisan III Corps was to advance into western Serbia, but this attempt was foiled by 'Maibaum'.
The two Yugoslav divisions were meet by a determined resistance by German, Bulgarian, pro-German Serb and Četnik forces, and forced to turn to the north-west. Tito and his staff believed that the Germans were unaware of their plan, but their radio communications were being monitored by Germans, who easily broke the partisan codes and were thus in complete possession of the details of the plan and therefore well able to lay their own preparations.
Initially the Germans ordered only General Major Simeon Simov’s Bulgarian 24th Division together with Četnik and Serb collaborationist forces to halt the partisan advance, but these proved inadequate and General Hans-Gustav Felber, the Militärbefehlshaber 'Südost', began preparation for a large-scale operation involving some 22,000 Axis troops. The German units included the 4th Regiment of Generalmajor Alexander von Pfuhlstein’s Division 'Brandenburg', 696th Feldgendarmeriebataillon (mot.), 3/2nd and 7/2nd Polizeiregiment, 2/3rd Polizeiregiment, two companies of Generalleutnant Otto Gullmann’s 297th Division, elements of Boris F. Shteyfon’s Russkiy Okhranniy Korpus (later Russisches Schutzkorps and later still Russisches Schutzkorps Serbien), 10 tanks of the 5th SS Polizeiregiment and, to secure local railways, the 205th Panzerzug and 301st Panzerzug armoured trains.
The Bulgarian formations were the 24th Division and General Major Nikola Grozdanov’s 25th Division. The Serb State Guard units were the 'Tranvski' District Company, 'Zički' District Company and 'Kraljevac' District Company, while the Serb Volunteer Corps' units were the 1/1st Regiment, 2nd Regiment and 4th Regiment. The 10,000 Četniks came from the Pozega Corps, 1st and 2nd Takovo Brigades of the 1st Ravna Gora Corps, 2nd Ravna Gora Corps, Lieutenant Colonel Dragutin Keserović's Rasinski Corps, Javorski Corps and 2nd Kosovo Corps.
After two months of heavy fighting, both of the partisan divisions were forced to retreat back to Sandak after suffering comparatively heavy losses: the 2nd Proletarian Brigade lost 34 men killed, 101 wounded and 60 missing, while the 5th Division lost 106 men killed, 324 wounded, 15 died from wounds and disease, and 27 missing.