The 'Battle of Kozara' which was also known as the 'West-Bosnien' operation, was fought on and round the mountain of Kozara in north-western Bosnia between Axis (German, Croat and Hungarian) forces and Yugoslav partisans (10 June/17 July 1942).
This was an important battle of the Yugoslav partisan resistance movement in World War II, and later became an integral part of Yugoslav post-war mythology, which celebrated the courage and martyrdom of outnumbered and outgunned partisans and civilians.
The battle was fought between German, Croat and Hungarian forces against the partisan forces of Josip Broz Tito in the Kozara mountain area between Banja Luka and Prijedor of Axis-occupied Yugoslavia (10 June/17 July 1942).
In this area, the 2nd 'Krajiski' Partisan Detachment was concentrated. In the spring of 1942 the partisan forces in central and western Bosnia had liberated Bosanski Petrovac, Drvar, Glamoč and Prijedor, and on 20 May the 2nd 'Krajiski' Partisan Detachment had been established, on the following day obtaining a limited number of armoured fighting vehicles and aircraft with which to hold the newly liberated territory stretching from the Sava river to the south across the Kozara and Grmeč mountains.
The German and Croat forces realised that the city of Banja Luka and the iron mine in Ljubija were threatened, and therefore planned 'West-Bosnien' to destroy the partisan forces with forces that fluctuated with time between 35,000 and 40,000 men (15,000 Germans and between 20,000 and 25,000 Croats). The Germans contributed some 15,000 men, the Croats about 22,000 home army and Ustase soldiers, and the Hungarians their Danube Flotilla (four river monitors, four gunboats and two armoured boats). The German forces comprised Generalmajor Heinrich Borowski’s 704th Division, elements of Generalleutnant Friedrich Stahl’s 714th Division, elements of Generalleutnant Johann Fortner’s 718th Division, the 521st Nahrichtenregiment, elements of the 202nd Panzerabteilung, the 924th Landesschützenbataillon, the 8th Landesschützenbaubataillon, and the 23rd Panzerzug armoured train; the Croat forces comprised Pukovnik Artur Gustović's 1st Mountain Division (with the 1st and 2nd Mountain Brigades), the 3rd and 4th Mountain Brigades, the Banja Luka Brigade, the 1, 2 and 3/Petrinja Brigade, elements of the 1st, 2nd, 5th, 10th, 11th and 12th Regiments, elements of the 1st Domobran Assault Battalion, the 4th, 5th, 6th, 7th, 8th, 12th, 13th and 18th Ustase Battalions, the Sanski Most, Kotoriste, Brozani Majdan and Banja Luka Volunteer Battalions, the Suhača Volunteer Company, the Prinz Eugens Volksdeutsch Battalion, the Ludwig von Badens Volksdeutsch Battalion, the 1st, 7th, 10th and 11th Recruit Battalions, elements of the 1st, 3rd, 4th and 8th Artillery Groups, two pioneer companies, one railway engineer company, the 4th Motor Transport Battalion, the 2nd Gendarmerie Battalion, about 2,000 Četnik auxiliaries, the Air Group Cenić (single fighter, bomber and mixed squadrons), and the 1st Air Force Field Company.
The partisans totalled between 3,000 and 3,500 men in five battalions, but were able to recruit reserves from the 60,000 civilians of the liberated area.
Starting on 10 June, 'West-Bosnien' developed as one of the largest, bloodiest and longest anti-partisan operations carried out in Croatia, and came to be seen by the German and Croat high commands as a major success. In the bitter fighting which followed the Axis forces' encirclement of the liberated area, some partisan units managed to break out during the night of 3/4 July, but the main group again came under close attack during the following night and was largely destroyed. In Siroka Luka about 500 wounded partisans were killed. Only small numbers of partisans managed to get away by burying their weapons, disguising themselves as civilian refugees, and passing through the Axis lines.
According to the Germans, the results up to 31 July, which included a two-week period of mopping up after the end of the main fighting on 17 July, the German losses were 69 men killed, 160 wounded and seven missing, the Croat losses 445 men killed, 654 wounded and 498 missing, and the partisan losses 4,310 persons killed and 10,704 taken prisoner. Post-war Yugoslav accounts admitted to only 1,700 killed, wounded and missing from the 2nd 'Krajina' Assault Brigade, the huge difference in the totals resulting from the Axis forces' listing of several thousand civilian dead as partisan auxiliaries.
Some 75,000 civilian refugees were driven out of their villages in the Kozara area, and many of these villages were then burned to the ground. Looting was common and atrocities were numerous. Of the refugees, 68,000 were forced into transit and detention camps, where 'selections' were then made for slave labour service.
About 900 partisans survived and were re-established as the 5th 'Krajina' Brigade. At the same time, and under Tito’s personal leadership, the main partisan group moved from eastern to western Bosnia and, after most of the Axis force had been pulled out, recovered parts of lost area in September 1942.