Slovene Lands in World War II World War II in the Slovene Lands started in April 1941 and lasted until May 1945 . Slovenia was during WWII in a unique situation in Europe , only Greece shared its experience of being trisected , however , Slovenia was the only one that experienced a further step — absorption and annexation into neighboring Nazi Germany , Fascist Italy , and Hungary . The Slovene - settled territory was divided largely between Nazi Germany and the Kingdom of Italy , with smaller territories occupied by Hungary , and the Independent State of Croatia . Occupation , resistance , collaboration , civil war , and post - war killings . On 6 April 1941 , Yugoslavia was invaded by the Axis Powers . On that day , part of the Slovene - settled territory was occupied by Nazi Germany . On 11 April 1941 , further parts of the territory were occupied by Italy and Hungary . The Germans occupied the Upper Carniola , the Lower Styria , the northwestern part of Prekmurje and the northern part of the Lower Carniola . The Italians occupied the Inner Carniola , the majority of the Lower Carniola and Ljubljana , whereas the Hungarians occupied the major part of Prekmurje . Resistance of the Kingdom of Yugoslavia ' s army was insignificant . In 2005 , Slovene authors first published information about six villages in Lower Carniola that were annexed by the Independent State of Croatia , and a Maribor - based historian first published original research about it in 2011 , but it remains unclear why the villages from Drava Banovina were occupied contrary to a known German - Croatian treaty . Under the Nazi occupation . The Nazis had a plan of ethnic cleansing of northern Slovenia , with the exception of north - eastern part that was occupied by Hungary , and they resettled or chased away Slovene civil population to the puppet states of Nedić ' s Serbia and NDH . Because Hitler opposed having the ethnic German Gottscheers in the Italian occupation zone , they were moved out of it . About 46 , 000 Slovenes were transported to Saxony in Germany in order to make space for the relocated Gottscheers . The majority of Slovene victims during the war were from the northern Slovenia , i . e . Lower Styria , Upper Carniola , Central Sava Valley , and Slovenian Carinthia . However , their formal annexation to the " German Reich " was postponed because of the installation of the new " Gauleiter " and " Reichsstatthalter " of Carinthia first , and later the Nazis dropped the plan because of the Slovene Partisans , with which they wanted to deal first . Only Meža valley initially became part of " Reichsgau Carinthia " . Under the Fascist Italy ' s occupation . Compared to the German policies in the northern Nazi - occupied area of Slovenia and the forced Fascist italianization in the former Austrian Littoral that was annexed after the First World War , the initial Italian policy in the central Slovenia was not as violent . Tens of thousands of Slovenes from German - occupied Lower Styria and Upper Carniola escaped to the Province of Ljubljana until June 1941 . However , after resistance started in Province of Ljubljana , Italian violence against the Slovene civil population easily matched that of the Germans . The province saw the deportation of 25 , 000 people — which equated to 7 . 5 % of the total population of the province — in one of the most drastic operations in the Europe that filled up many Italian concentration camps , such as Rab concentration camp , in Gonars concentration camp , Monigo ( Treviso ) , Renicci d ' Anghiari , Chiesanuova and elsewhere . To suppress the mounting resistance by the Slovene Partisans , Mario Roatta adopted draconian measures of summary executions , hostage - taking , reprisals , internments , and the burning of houses and whole villages . The " 3C " pamphlet , tantamount to a declaration of war on civilians , involved him in Italian war crimes . A barbed wire fence - which is now Path of Remembrance and Comradeship - was put around Ljubljana in order to prevent communication between the city ' s underground activists in Ljubljana and the majority of partisans in the surrounding countryside . Resistance . On 26 April 1941 , several groups formed the Liberation Front of the Slovene Nation , which was the leading resistance force during the war . The front was initially a democratic platform . With the Dolomiti Declaration , signed in March 1943 , the Communists , however , monopolized it . It emitted its own radio program called " Kričač " the location of which never became known to occupying forces and they had to confiscate the receivers ' antennas from the local population in order to prevent listening to the radio of the Slovene Liberation Front . Its military arm was the Slovene Partisans . The Slovene Partisans retained their specific organizational structure and Slovene language as their commanding language until the last months of World War II , when their language was removed as the commanding language . In March 1945 , the Slovene Partisan Units were officially merged with the Yugoslav Army and thus ceased to exist as a separate formation . At the very beginning Slovene Partisan forces were relatively small , poorly armed and without any infrastructure , but Spanish Civil War veterans amongst them had some experience with guerrilla methods of fighting the enemy . The partisan activities in the Slovene Lands were initially independent of Tito ' s Partisans in the south . In autumn 1942 , Tito attempted for the first time to control the Slovene resistance movement . The merger of the Slovene Partisans with Tito ' s forces happened in 1944 . In December 1943 , Franja Partisan Hospital was built in difficult and rugged terrain , deep inside German - occupied Europe , only a few hours from Austria and the central parts of the Third Reich . German military activity was frequent in the general region throughout the operation of the hospital . It saw continuous improvements until May 1945 . Civil war and post - war killings . In the summer of 1942 , a civil war between Slovenes broke out . The two fighting factions were the Slovenian Partisans and the Italian - sponsored anti - communist militia , known as the White Guard , later re - organized under Nazi command as the Slovene Home Guard . Small units of Slovenian Chetniks also existed in Lower Carniola and Styria . The Partisans were under the command of the Liberation Front ( OF ) and Tito ' s Yugoslav resistance , while the Slovenian Covenant served as the political arm of the anti - Communist militia . The civil war was mostly restricted to the Province of Ljubljana , where more than 80 % of the Slovene anti - partisan units were active . Between 1943 – 1945 , smaller anti - Communist militia existed in parts of the Slovenian Littoral and in Upper Carniola , while they were virtually non - existent in the rest of the country . By 1945 , the total number of Slovene anti - Communist militamen reached 17 , 500 . Immediately after the war , some 12 , 000 members of the Slovene Home Guard were killed in the Kočevski Rog massacres , while thousands of anti - communist civilians were killed in the first year after the war . These massacres were silenced , and remained a taboo topic until an interview with Edvard Kocbek was published by Boris Pahor in his publication Zaliv , causing the 1975 Zaliv Scandal in Titois Yugoslavia . End of war and aftermath . World War II in the Slovene Lands lasted until the middle of May 1945 . On 3 May , the National State of Slovenia was proclaimed as part of the Kingdom of Yugoslavia . The liberation of Ljubljana , the capital city of the now independent Slovenia , was announced on 9 May 1945 . The last battle was the Battle of Poljana , which took place near Prevalje on 14 and 15 May 1945 , a few days after the formal surrender of the Nazi Germany . Hundreds of ethnic Italians from the Julian March were killed by the Yugoslav Army and partisan forces in the Foibe killings ; some 27 , 000 Istrian Italians fled Slovenian Istria from Communist persecution in the so - called Istrian exodus . Members of the ethnic German minority either fled or were expelled from Slovenia . Number of victims . The overall number of World War II casualties in Slovenia is estimated at 97 , 000 . The number includes about 14 , 000 people who were killed or died for other war - related reasons immediately after the end of the war , and the tiny Jewish community , which was nearly annihilated in the Holocaust . In addition , tens of thousands of the Slovenes left their homeland soon after the end of the war . Most of them settled in Argentina , Canada , Australia and in the USA . The overall number of World War Two casualties in Slovenia is estimated to 89 , 000 , while 14 , 000 people were killed immediately after the end of the war . The overall number of World War II casualties in Slovenia was thus of around 7 . 2 % of the pre - war population , which is above the Yugoslav average , and among the highest percentages in Europe . Non - extradition of the Italian war criminals . The documents found in British archives by the British historian Effie Pedaliu and by Italian historian Davide Conti , pointed out that the memory of the existence of the Italian concentration camps and Italian war crimes has been repressed due to the Cold War . Yugoslavia , Greece and Ethiopia requested extradition of 1 , 200 Italian war criminals who however never saw anything like Nuremberg trial . The extradition never took place because the western allies ' governments saw in Pietro Badoglio ' s government a guarantee of an anti - communist post - war Italy .