After the kingdom of Yugoslavia capitulated to Germany in April 1941, Hitler divided the country among the Axis states. Germany annexed most of Slovenia, occupied Serbia, and administrated eastern Vojvodina. Italy annexed or occupied much of the Croatian coastland, southern Slovenia, western Macedonia and Kosovo, and tried in vain to control Montenegro by means of an autonomous administration. Hungary annexed the remainder of the province of Vojvodina and eastern Slovenia. Bulgaria took Macedonia and a sliver of southeastern Serbia.

The occupiers established puppet regimes. Croatia, Bosnia and Herzegovina were put in the charge of a Croatian nationalist group, the fanatical Ustashas, whose leaders had spent the 1930s as Mussolini’s clients and sometimes his prisoners. The poglavnik (equivalent to führer) of the self-styled Independent State of Croatia (Nezavisna Drzava Hrvatska, NDH) was Ante Pavelic. Its leaders were obsessed with eliminating the Serb Orthodox population, which was seen as the historic obstacle to Croatian sovereignty.

The NDH’s population of 6.3 million included only 3.4 million Croats. The remainder were mostly Serb (1.9 million), Muslim (700,000), German (150,000) and Jewish (37,000). In line with Axis policy, the Ustashas deported and killed Jews and Roma. The Serb population was the strategic target, however, owing to its size and to Ustasha ideology. At least 20,000 Serbs were killed in pogroms during summer 1941. By 1945, in line with the Ustasha intention to eradicate the Serb Orthodox population by mass conversion, expulsion, and murder, enough death and destruction had been achieved to make the NDH the bloodiest regime in Europe after Germany itself.

In Serbia, the Nazis formed a “government of national salvation” under Milan Nedic, who saw himself as caretaking until the royalist government could return from exile in London. Pavelic’s equivalent in Belgrade was Dimitrije Ljotic, who received limited German support for his Serbian fascist movement. Even without an ideology of genocide, Nazi mechanisms functioned efficiently and the situation for Jews and Roma was no better than in Croatia. Serbia was proclaimed Judenfrei (Free of Jews) in early 1942.

Some army officers took to the hills and formed a royalist resistance movement, the Chetniks, loyal to the royalist government but also to a Serbian nationalist program. Savage Nazi reprisals in Serbia in 1941 soon quieted this movement’s anti-German actions, but it continued to commit atrocities against Croats and Muslims in the NDH. Proportionately, Muslim losses in the war were heavier than Serb or Croat losses.

Croatian and Serbian nationalist crimes strengthened the resistance movement launched in summer 1941 by the Communist Party of Yugoslavia under a shadowy figure called Josip Broz, later known as Tito, who was supported by the USSR. The engorged but Axis-occupied Croatian state became the principal battleground between the partisans and their pro-fascist or anti-communist opponents, with each side’s armed forces numbering around 150,000 by 1943.

At least a million Yugoslavs (6% of the pre-war population) were killed between 1941 and 1945, mostly at their compatriots’ hands. The killing continued after the war, as Tito’s victorious forces took revenge on their real and perceived enemies. British forces in Austria turned back tens of thousands of fleeing Yugoslavs. Estimates range from 30,000 to 55,000 killed between spring and autumn 1945.

Native German and Hungarian communities, seen as complicit with wartime occupation, were brutally treated; tantamount in some cases to ethnic cleansing. The Volksdeutsch settlements of Vojvodina and Slavonia largely disappeared. Perhaps 100,000 people—half the ethnic German population in Yugoslavia—fled in 1945, and many who remained were compelled to do forced labor, murdered, or later ransomed by West Germany. Some 20,000 Hungarians of Vojvodina were killed in reprisals. Albanian rebellions in Kosovo were suppressed, with prisoners sent on death marches towards the coast. An estimated 170,000 ethnic Italians fled to Italy in the late 1940s and 1950s. (All of these figures are highly approximate.)

The partisans were not always ruthless to their wartime opponents. By contrast with Germany, however, the postwar order in Yugoslavia did not allow an impartial examination of the war years. Grief was made more bitter by the anger and vengefulness of those whose struggles and sufferings were officially distorted or denied. Tito’s regime created an official celebratory myth about the “People’s Liberation War,” denying partisan atrocities and negotiations with Germans and exaggerating their role in defeating the Axis. While this helped to unify the traumatized nationalities in the wake of fascism’s defeat, it could not silence the truths and counter-myths handed down within families throughout Yugoslavia and nursed among Serb and Croat émigrés. In particular, many Croats came to resent what they saw as excessive attention to the Ustasha regime and a corresponding exculpation of Serbian nationalist crimes. By the time Titoist orthodoxy relaxed and the archives yielded their secrets, in the 1980s— confirming that the partisans’ black-and-white, epic version had concealed an unsurprising pattern of shifting allegiances and power—plays in which Tito’s forces eventually bested their enemies—it was too late for reconciliation.