'Ungewitter' was a German and Croat operation against the partisan forces of Marshal Josip Broz Tito in the Papuk mountain region of the puppet state of Croatia in German-occupied Yugoslavia (24 April/8 May 1944).
The undertaking’s objective was to encircle and destroy the partisan forces of the Yugoslav VI Corps (12th and 28th Divisions) in the Papuk mountain region centred some 12.5 to 15.5 miles (20 to 25 km) to the north-north-west of Slavonska Pozega in Slavonia.
The Germans contributed Generalleutnant Walter Jost’s 42nd Jägerdivision, 2/92nd Grenadierregiment (mot.), 468th Panzerspähkompanie zbV, Stab/1st Polizei-Freiwilligen-Regiment 'Kroatien', 6th and 9th Polizei-Freiwilligen-Bataillone (kroatische), 11th Polizei-Panzer-Kompanie 'Kroatien', 2nd Polizei-Geschütz-Batterie 'Kroatien', 12th Panzer-Kompanie zbV with five Italian assault guns and eight French light tanks, and elements of the 606th Sicherungsregiment, while the Croats contributed Pukovnik Stjepan Grlić's 4th Mountain Brigade, 2nd Battalion of Pukovnik Aurel Schlacher’s Mobile Brigade, 15th, 16th and 18th Battalions of Ustase Dopukovnik Ivan Stir’s 2nd Ustase Brigade, and one light tank platoon of the 4th Mountain Brigade.
The Germans and Croats began closing on their target area from Virovitica, Podravska Slatina, Daruvar, Nasice and Slavonski Pozega on 27 April. Over the next 12 days, the Axis forces steadily combed the operational area’s mountainous terrain, frequent skirmishes occurring as the partisans tried to avoid direct confrontation with the numerically superior Axis forces, while at the same time protecting their camps and supply dumps in the woods. The Axis forces destroyed all the camps and buildings they discovered, burned down a number of villages and killed many civilians on the grounds, right or wrong, that they were partisan sympathisers. Most of the partisans succeeded in escaping the Axis cordon.
The Germans admitted that they and the Croats had lost 63 men killed, 134 wounded and 46 missing, and claimed to have inflicted on the partisans losses of 417 men counted dead and 760 estimated dead, 191 counted wounded and 297 estimated wounded, and 141 taken prisoner. Heavy fighting in fact continued after operation’s official end, and the Axis failure to eliminate this partisan force required the launch of a new offensive against the 12th 'Slavonia' Division in the second half of the May by Generalleutnant Helmuth von Pannwitz’s 1st Kosaken-Kavalleriedivision and a Gebirgsjägerbrigade in the region of Dilj and south-east of the Pozega valley.