This was a German operation against so-called partisans in the region of Polotsk, Borisov and Lepel in the German-occupied western USSR (3/23 June 1943).
The region in which the operation was undertaken lay in the rear of Generaloberst Hans-Georg Reinhardt’s 3rd Panzerarmee, which held the northern shoulder of Generalfeldmarschall Günther von Kluge’s Heeresgruppe ‘Mitte’, and was the operational sector allocated to General Andrei I. Eremenko’s Kalinin Front (later 1st Baltic Front) in the Soviet offensive planned for the late summer of 1943. The partisan forces were thus tasked with creating havoc on German lines of communication in an effort to divert German front-line units and to hinder defensive preparations. During the course of the operation some 5,000 persons were executed on suspicion of being collaborators. Despite the high death toll they exacted, the Germans captured only 492 rifles, thereby providing good evidence that most of the dead were merely members of the local population and not partisans.
(It is worth noting that until the start of the 20th century the spelling of this German city’s name was contentious: in Berlin the spelling Kottbus was preferred and is still in limited use, but locally the traditional spelling Cottbus was preferred. Thus the operations for which this city’s name was used are sometimes rendered as 'Kottbus'.)