'Pfingsten' was a German and Croat operation against the partisan forces of Josip Broz Tito in the area of Prnjavor, Kotor Varos and Teslić in the puppet state of Croatia in Axis-occupied Yugoslavia (13/16 June 1943).
During the Axis forces' 'Schwarz' (ii) offensive, partisan units across Yugoslavia received orders to to launch a series of attacks to relieve the Axis pressure on the surrounded partisan main group around Tito and to prevent the Germans from despatching reinforcements once they had effected their breakthrough. One of the most rapid of responses to this call occurred at the village of Vijačana near Prnjavor, where the 5th 'Kozara' Brigade captured two companies of the Croat army’s 2/1st Recruit Regiment together with three 100-mm (3.94-in) howitzers and 600 rounds of ammunition, 150 rifles with 25,000 rounds of ammunition, three heavy and eight light machine guns, and one mortar.
The fighting in this area continued on 4/5 June 1943, forcing the staff of Generalleutnant Karl Eglseer’s 114th Jägerdivision to establish the Kampfgruppe 'Huwe' from the 721st Jägerregiment reinforced with Croat army and Četnik elements and supported by an artillery battalion to make an air-supported attack and destroy the 5th 'Kozara' Brigade.
The Kampfgruppe 'Huwe' was defeated on the slopes of the Ljubić mountain, and this prompted the creation of a larger anti-partisan operation. The object of the undertaking was the pinning and destruction of the partisans' 12th 'Krajina' Division in the mountainous area of central Bosnia bounded by Prnjavor, Kotor Varos and Teslić. The Germans contributed the 721st Jägerregiment, and the Croats the 1st Jäger Regiment, three battalions of the 8th Regiment, 3/5th Regiment, and two mountain batteries of the 6th Artillery Group, as well as the Četnik 'Borja' and 'Obilić' Detachments.
From 05.00 on 13 June, with columns advancing from Banja Luka, Kotor-Varos, Teslić, Derventa and Prnjavor toward the villages of Vrsani, Vijačani, Kokori and Maslovare as well as the Uzlomac mountain area, the 12,000-man Axis force made contact with the partisans, and there followed a short but intense firefight before the various elements of the 12th 'Krajina' Division made good their escape, claiming an estimated 200 German and Croat casualties, including 90 dead, without any mention of their own losses. No German loss figures have been found for this operation, and thus the partisan casualties cannot even be estimated.
Believing that the partisans had sustained heavy losses, the Četnik forces returned to area between Vrbanja and Vrbas only to be attacked on 24 June by the 5th and 12th 'Krajina' Brigades of the 11th 'Krajina' Division and the 'Banja Luka' Partisan Detachment, which pursued them back to Banja Luka.