For centuries, the eastern Adriatic coast was a patchwork of Italian-speaking coastal cities and Slavic-speaking rural communities. The Republic of Venice governed parts of Istria and Dalmatia from the ninth century until its fall in 1797, and Italian language and culture dominated urban life in cities like Pola, Trieste, and Zara. After the Napoleonic Wars, the region passed to the Austrian Empire, where Italian irredentism grew among those who wanted unification with Italy. After World War I, the Treaty of Rapallo gave most of Istria and Trieste to Italy. What followed was Fascist oppression: Mussolini's regime banned Croatian and Slovenian languages from schools and public life, suppressed Slavic cultural organizations, and imposed forced Italianization on communities that had lived in these lands for generations. This calculated erasure of Slavic identity created a reservoir of grievance that the violence of the 1940s would exploit.

The massacres occurred in two distinct waves. The first came in September 1943, in the chaos following Italy's armistice with the Allies. With Italian authority suddenly dissolved, spontaneous revenge killings erupted across Istria. Croats and Slovenes who had suffered twenty years of Fascist repression turned on local Fascist Party members, Italian landowners, policemen, and civil servants. Victims numbered in the hundreds. The fire brigade of Pola recovered 204 bodies from the foibe of the region between October and December 1943. The second wave, far larger and more organized, followed the Yugoslav occupation of the region in May 1945. This was not spontaneous violence but systematic action by Yugoslav security forces, targeting not only Fascist collaborators but also anti-Fascists who opposed Yugoslav annexation, autonomists, and civilians perceived as threats to the new order. Among those killed were Socialist leader Licurgo Olivi, Resistance leader Romano Meneghello, and Dachau survivor Angelo Adam.

The true toll remains contested. Historians Raoul Pupo and Roberto Spazzali estimated approximately 3,000 to 5,000 total victims, noting that targets were primarily military and repressive forces of the Fascist regime along with civilians associated with it. Other estimates run higher. A joint Slovene-Italian historical commission established in 1993 documented hundreds of summary executions and mass deportations from which many never returned. Italian authorities recovered 369 bodies from foibe and 95 from mass graves in their zone of the Free Territory of Trieste between 1945 and 1948, including the remains of German soldiers hastily buried in the closing days of the war. The foibe on the Yugoslav-controlled side were never searched. At least 23 percent of documented victims from Italian-majority Trieste were Slavs or had at least one Slavic parent, a reminder that the violence, though primarily directed at Italians, consumed people from both communities.

The killings were prologue to a larger catastrophe. Between 1943 and the early 1950s, the vast majority of ethnic Italians left Istria and Dalmatia. They departed from communities where their families had lived for centuries, from cities where Italian had been the language of commerce and culture since the Middle Ages. The joint Italian-Slovene commission noted that the majority of this exodus happened in the early 1950s, years after the worst violence, when it became clear these territories would remain permanently Yugoslav. War-caused economic hardship and repressive postwar policies, including nationalization, expropriation, and discriminatory taxation, left Italian families with little reason to stay. Today, the Croatian census records approximately 19,636 Italians in the country, and Slovenia records 2,258. In Dalmatia, where Italian-speakers once comprised 20 percent of the population, only around 500 remain. The absence is a kind of presence, written into the bilingual street signs of Istrian towns and the curriculum of Italian-language schools that still operate in Rovinj, Pula, and Rijeka.