It was the second act of mass murder committed by the Ustaše upon coming to power and was part of a wider campaign of genocide against Serbs in the NDH that would last until the end of the war.

The victims were drawn from the village of Veljun and its surroundings, ostensibly for their involvement in the robbery and murder of a local Croat Catholic miller, Joso Mravunac, and his family.

These plans fell apart after Mravunac's surviving daughter was unable to identify perpetrators from a police lineup and prosecutors declined to launch proceedings against any individual without evidence of their guilt.

Dissatisfied, Vjekoslav Luburić, a senior Ustaše official, arranged for the creation of a new "special court" and appointed a prosecutor that was unwilling to let the lack of evidence hinder a conviction.

The Ustaše went further and executed all of the men in their custody in a pit behind the Blagaj school, burying their bodies in a mass grave, which was subsequently covered with crops.

The inhabitants of the two villages began returning to the region after the war, but tensions persisted, and an attempt to commemorate the massacre in May 1999 resulted in the socialist-era monument to the victims being desecrated.

[1] Following the 1938 Anschluss between Germany and Austria, Yugoslavia came to share its northwestern border with the Third Reich and fell under increasing pressure as her neighbours aligned themselves with the Axis powers.

[7] Intending to secure his southern flank for the impending attack on the Soviet Union, Adolf Hitler began placing heavy pressure on Yugoslavia to join the Axis.

Two days later, a group of pro-Western, Serbian nationalist Royal Yugoslav Air Force officers deposed the country's regent, Prince Paul, in a bloodless coup d'état, placed his teenaged nephew Peter on the throne, and brought to power a "government of national unity" led by General Dušan Simović.

[10][11] To make matters worse, many of the VKJ's non-Serb personnel, especially Croats, were reluctant to fight against the Germans, whom they considered liberators from decades of Serb oppression.

[10][12][13] On 10 April, senior Ustaše leader Slavko Kvaternik proclaimed the establishment of the Independent State of Croatia (Nezavisna Država Hrvatska, NDH).

On 15 April, Pavelić reached Zagreb, having granted territorial cessions to Italy at Croatia's expense and promised the Germans that he had no intention of pursuing a foreign policy independent of Berlin.

The following day, investigative judge Nikola Lasić and county commissioner Eduard Lenčeric filed a report describing the incident as a "murder-robbery by unknown perpetrators".

Local Ustaše officials dismissed these findings and suggested that the deaths could be attributed to "Chetniks"[a] from the nearby village of Veljun, whose population was predominantly Serb.

[22] On 6 May, NDH Justice Minister Mirko Puk requested that Vladimir Židovec, the secretary of the Karlovac Ustaše Council, select local lawyers deemed "certified good Croats" to prosecute Serbs suspected of involvement in the Mravunac murders.

[22] That evening, Puk dispatched messengers from the Karlovac Ustaše Council, telling the lawyers he had selected that they should be ready to depart for Blagaj by 05:00 the following morning.

According to the subsequent corroborating statements of Betlehem, Stilinović and Lukinić, the members of the "people's court" encountered a large group of prisoners at the Blagaj school, many of whom had visibly been beaten or otherwise tortured.

According to Ustaše records, the following afternoon, 32 individuals were sentenced to death by firing squad for "an attempted Chetnik uprising against the Independent State of Croatia and the murder of the Croatian family Mravunac".

After the war, Dušan Nikšić, the only survivor from this group, stated that 36 people were convicted and immediately taken to the execution site, a pit behind the Blagaj school.

[26] Several accounts suggest that the men brought along by Luburić and Šarić participated more extensively in the torture and killing of civilians while local Ustaše activists only assisted and stood guard.

[30] One Croat woman from Blagaj stated that her husband's participation in the massacre, though limited to guarding the prisoners, left him feeling ill and unable to eat or sleep for several days.

"The entire village knew what had happened that night behind their school," the Holocaust scholar Slavko Goldstein writes, "and they participated in a conspiracy of silence that lasted three full months."

[33] After the war, which ended with the destruction of the NDH and re-establishment of Yugoslavia as a socialist state, the inhabitants of Veljun denied that any locals had taken part in the killings.

[35] Pavelić fled to Argentina, survived an assassination attempt by Yugoslav government agents in Buenos Aires in 1957, and died of his wounds in Madrid two years later, aged 70.

[33] The monument, erected by Yugoslavia's socialist government, evasively described the perpetrators as "fascists" rather than explicitly calling them Ustaše, part of an attempt at fostering cooperation and reconciliation among the country's ethnic groups.

In private, the residents of Blagaj blamed Chetniks from Veljun, Poloj and other Serbian villages for initiating an uprising against the NDH and killing the Mravunac family, for which no more than 150 were tried and executed in accordance with the law.

[42] The historians Philip Cook and Ben Shepherd note that the atrocities that took place in April and May 1941, such as those at Gudovac, Blagaj and Glina, occurred before any organized uprising by either the Partisans or Chetniks.

That same year, all the remaining residents of Blagaj and Pavlovac were forced from their homes by Croatian Serb rebels, amid inter-ethnic warfare sparked by the breakup of Yugoslavia.

In August 1995, the Croatian Army recaptured all the rebel-held areas in central Croatia, forcing the residents of Veljun and surrounding Serb villages to flee.

[45] Annual commemorations have resumed since then, though tensions persist, owing primarily to disputes over the number of victims and disagreement over who killed the Mravunac family.