Case White Case White ( ) , also known as the Fourth Enemy Offensive ( ) was a combined Axis strategic offensive launched against the Yugoslav Partisans throughout occupied Yugoslavia during World War II . It is one of the most significant confrontations of the Yugoslav Front . The offensive took place in early 1943 , between 20 January and mid - to - late March 1943 . The operation is most remembered in Yugoslavia for its final phase , the Battle of the Neretva ( " Bitka na Neretvi " ) named after the Neretva river . The final phase is also known as the Battle for the Wounded ( " Bitka za ranjenike " ) . Background . In late 1942 , with the Axis situation in North Africa deteriorating , the German high command became concerned about the possibility of an Allied landing in the Balkans . This was of particular concern due to the substantial resources they were extracting from Yugoslavia , including timber , copper and bauxite . In the event of an Allied landing , resistance forces in Yugoslavia would be likely to interfere with German defensive operations as well as continued resource extraction . As a result , on 16 December 1942 , Adolf Hitler ordered the Armed Forces Commander in South - East Europe , Generaloberst Alexander Löhr to crush the resistance in Yugoslavia . In a meeting of 18 – 19 December , the General Staff of the Wehrmacht decided on the destruction of the Bihać Republic . On 8 January , Löhr and Mario Roatta , commander of the 2nd Italian army , met in Zagreb and devised a detailed plan . Operation . The operation was planned to be carried out in three stages : The Germans aimed to destroy the central command of the Partisan movement , the Central Committee of Communist Party of Yugoslavia , as well as the main Partisan hospital . The Axis rallied ten divisions equaling 90 , 000 troops and in addition twelve air squadrons . Chetnik auxiliaries and formations consisting of between 12 , 000 and 15 , 000 men also took part and worked closely with the Italians . The operation coincided with the Chetnik ' s " March on Bosnia " which intended for Chetniks from Lika , northern Bosnia , northern Dalmatia , Herzegovina , and Montenegro to combine to destroy the core of the Partisan ' s territory and involved a genocidal attack on the Muslims in Bosnia and Herzegovina and in Sandžak . According to the Germans , the Chetniks stood at 150 , 000 men in February 1943 ( up from 100 , 000 in August 1942 ) . The Partisans on the other hand numbered less than a third of that figure . On 2 January , Mihailović reported to the Chetniks of his plan for the destruction of the Partian ' s Bihać Republic in order to " liberate this Serb territory from Communist terror " and on the 21st said " indeed , the question of Bosnia is most important . In western Bosnia and Lika we are currently making the final preparations for the definitive destruction of the Communists who are preventing us from destroying Pavelić ' s Croatia " . " On 20 January , " Weiss " 1 commenced and would last until 25 February . The Axis forces attacked the territory controlled by the Partisan 1st Croatian and 1st Bosnian Corps – the areas of Banija , Kordun , Lika and western Bosnia . The Partisan Chief Operational Group had left Bihać in late January and in the meantime tried to carry out the Supreme Staff ' s plan of moving its operations eastward . The Supreme Staff wanted its force to relocate from Bosnia and Herzegovina to Serbia while the Croatian and Bosnian Corps hold the line against the enemy . The Chief Operational Group , enlarged to include the 7th Banjia and the 9th Dalmatian Division s , struggled across south - west Bosnia while Axis forces gradually beat the Croatian and Bosnian Corps ' resistance . On 9 – 12 February , during its journey toward the Neretva river , the Chief Operational Group defeated the Italian Murge Division and gained control of Imotski , Ljubuški , Široki Brijeg , Prozor , and Jablanica . Battle of the Neretva . During the battle , the Partisans were caught in a pocket with their backs to the Neretva river . On their western side , were German forces , including several elite units and supported by panzer brigades . The eastern side ( opposite the Partisan pocket ) was guarded only by Chetnik formations , who were acting in coordination with the Germans . To reach this side the Partisans would have to cross one or more of the five bridges on the Neretva river . If the Partisans could cross the river they would be relatively safe ; however , they had insufficient time to cross as the Axis forces were preparing for their final push . In order to counter this strategic " checkmate " , the Partisan commander , Josip Broz Tito , prepared an elaborate deception . He ordered his sappers to actually blow up all the bridges on the river . When air reconnaissance brought this information to the German command , they concluded that the Partisans must be preparing a final dash north of their current position ( along the western shore of the Neretva ) , and had blown up the bridge to prevent desertion as well as attack by Chetnik forces from the other side of the river . They thus began a redeployment of troops in the area to block the anticipated movement . This redeployment gave the Partisan engineers precious time needed to sufficiently repair the bridge and to eliminate the Chetnik troops defending its far side . The Germans , characteristically , quickly caught on , but were unable to correct their mistake and prepare a serious attack in time , because of their previous redeployment orders . With their rearguard fighting off an increasingly powerful German advance , the Partisans crossed the river under intense air bombardment ( the Axis deployed large " Luftwaffe " formations ) , but the mountainous landscape prevented accurate destruction of the makeshift bridge . After the escape was complete , the weak bridge was finally rendered useless to prevent pursuit . The humiliating strategic defeat was amplified by Tito being able to keep his well known pledge not to leave the wounded behind , as they faced certain execution at the hands of the Axis ( which later actually happened in the aftermath of the Battle of the Sutjeska ) . The operation marked the " high point of Chetnik collaboration with the Axis powers " . In order to ensure the operation ' s success , Draža Mihailović relocated from Montenegro to Kalinovik where Zaharije Ostojić , commander of operations in Herzegovina , was situated . On 9 March , Mihailović informed Colonel Bajo Stanišić : Aftermath . By the end of March , the Germans claimed to had killed about 11 , 915 Partisans , executed 616 , and captured 2 , 506 . Despite these heavy losses and a tactical victory for the Axis powers , the partisan formations secured their command and the hospital , and were able to continue operations . In fact , once they reached the eastern parts of Bosnia and Herzegovina , the Partisans had to face only the Chetniks , and in turn almost entirely incapacitated them in the area west of the Drina river . The next major operation in Yugoslavia was Operation Schwarz . In popular culture . The 1969 Oscar - nominated motion picture " The Battle of Neretva " depicts these events . Alistair MacLean ' s 1968 thriller novel " Force 10 From Navarone " , subsequently filmed , also brings forth the fight of outnumbered Partisans against Germans and Chetniks , and the blowing up of the Neretva bridge . But the actual historical events are not in play , and the story is entirely fictional .