April 1941: Axis invasion of Yugoslavia

Following a military coup on 27 March 1941 that overthrew Yugoslavia’s pro-Axis government, the country was invaded by the European Axis beginning on 6 April 1941. Yugoslav forces were rapidly defeated and, on 18 April, the Yugoslav military commander signed a ceasefire for the unilateral and unconditional surrender of Yugoslavia. The Axis invasion coincided with a revolt that established a Croatian state under the fascist Ustaša and resulted in the division of Yugoslavia between Germany, Italy, Croatia, Bulgaria, and Hungary.

The Axis invasion of Yugoslavia was a direct response to a military coup on 27 March 1941 that overthrew the Yugoslav regent, Prince Pavle. This coup was motivated by opposition to Prince Pavle’s domestic policy of reconciliation between Serbs and Croats and his foreign policy of alignment with the Axis. Following his assumption of the regency, over the child King Petar II, following the assassination of King Aleksandr I in 1934, Prince Pavle tried to ease ethnic tensions that had arisen under King Aleksandr’s Serbian chauvinist government. These efforts culminated in the Cvetković–Maček Agreement of 1939, which established an autonomous Croatian province. Compromises with the Croats were deeply unpopular with the Serbian chauvinists in the military and Orthodox Church. Prince Pavle’s foreign policy also posed a threat as alliance with the Axis was thought to cement Prince Pavle’s personal power and, thus, make Croatian autonomy permanent. To prevent the Cvetković–Maček Agreement from becoming permanent and because of their own view that Yugoslav ascension to the Axis represented a dishonorable capitulation, the military reacted to the news that Prince Pavle had joined the Axis by overthrowing his government and installing the 17-year-old King Petar II on the throne in his own right. King Petar II then declared that Yugoslavia would not be a member of the Axis.

Hitler responded to the coup in Yugoslavia by ordering the invasion of the country. Hitler had pressured Yugoslavia into joining the Axis to secure his southern flank, particularly access to Romania’s oil fields, in preparation for an invasion of the USSR. Hitler viewed the new Yugoslav government’s exit from the Axis as both a personal betrayal that needed to be punished and a sign that Yugoslavia was not a reliable partner and needed to be occupied. Other members of the European Axis — Italy, Hungary, Bulgaria — had territorial disputes with Yugoslavia and used this opportunity to seize parts of the country.

The Yugoslav Army collapsed during the Axis invasion, as that invasion coincided with internal upheaval related to the coup, including mass mutiny and uprising by Croat nationalists. Within the first days of fighting, Croatian nationalists seized control of Zagreb and convinced large numbers of Croats and Slovenes in the Yugoslav army to mutiny or desert, causing Yugoslav lines to collapse in disarray. The military was unable to respond to the loss of large portions of its army and, after fighting with a disorganized army for several days, surrendered to the Axis. The Yugoslav royal family fled to Greece to establish a government-in-exile. Yugoslavia was split between Bulgarian, Hungarian, German, and Italian occupation, as well as the fascist Independent State of Croatia.

The Axis invasion of Yugoslavia allowed the Ustaša to come to power in Croatia, laying the groundwork for the genocide of Serbs, Jews, and Roma in Yugoslavia. The Ustaša, who had been chosen by the Germans and Italians to govern Croatia, believed that the existence of Serbs and Jews in their national territory was a threat to the continued existence of Croatia. Accordingly, they carried out mass killings of hundreds of thousands of Serbs as well as other ethnic minorities viewed as unwanted, particularly Jews and Roma. The genocide carried out in Croatia created deep-seated ethnic animosity in Yugoslavia, which motivated both the dissolution of Yugoslavia in the 1990s and the genocides that accompanied it.

Although the Axis Invasion of Yugoslavia was brief, the remaining elements of the Yugoslav army, as well as Communist partisans, initiated a guerrilla warfare campaign against occupying Axis forces. This partisan conflict in Yugoslavia seriously challenged Axis control over Yugoslavia and required the deployment of hundreds of thousands of German and Italian soldiers to combat. The Axis soldiers fighting in Yugoslavia, approximately 300,000 Germans and 300,000 Italians in 1943, were forces that could not be deployed to other theaters. The Axis decision to invade Yugoslavia thus put serious strain on Axis manpower resources and tied down soldiers who otherwise could have shifted the balance on the Eastern Front in favor of the Axis.