Leo Petrović

Petrović's doctoral thesis titled "Disquisitio historica in originem usus Slavici idiomatis in liturgia apud Slavos ac praecipue Chroatos dissertatio" from the University of Fribourg was published in Latin by the Croatian Joint-stock Printing House in 1908. His doctoral thesis was translated into Croatian by Šime Demo and republished as a chapter titled "Povijesno istraživanje o početku uporabe slavenskoga jezika u liturgiji kod Slavena, napose Hrvata" in the biographical book about him authored by Ante Marić titled Leo Petrović prvi hercegovački franjevac doktor znanosti (Leo Petrović – the first Franciscan Doctor of Science), published in 2008 by the Franciscan Province of Herzegovina.[11]

Petrović was the first historian to rebuke the Bogomilist theory about the Bosnian Church in a paper titled "Krstjani Crkve bosanske" (Chrisitans of the Bosnian Church) from 1944. He was also the first historian to refer to them as Christians, as they called themselves, instead of referring to them by other ideological names.[12] He promoted a thesis that the Bosnian Church had origins in the Catholic Benedictine monastic order,[13][14] and considered that the Bosnian Church used native language, but observed the Roman Rite.[15] His paper was published only after his death in 1953, and republished again in 1999 by the Franciscan Province of Herzegovina.[12]

Petrović also wrote about the Glagolitic priests in Herzegovina, publishing four articles on them in the Catholic periodical "Kršćanska obitelj" (the Christian family) in 1939.[2] Petrović published a number of scientific articles in various periodicals.[6]

After the German invasion of Yugoslavia in April 1941, Petrović was arrested by the Yugoslav police on 15 April, where he remained for a day and was nearly murdered. The next day, he and Cvitan Spužević, a notable Croat lawyer from Mostar, organised peace talks between the warring sides. The tensions between Croats and Serbs were high. The situation worsened after the German invasion of the Soviet Union in June 1941 and the uprising of Serbs in eastern Herzegovina. The authorities of the newly established Independent State of Croatia (NDH) started mass arrest and killings of Serbs between 25 and 26 June 1941.[16]

Petrović publicly opposed the NDH regime because of its persecution of Serbs. He met with Poglavnik Ante Pavelić, the leader of the NDH regime in Zagreb somewhere at the end of June or beginning of July 1941 and requested an end to the persecution of Serbs. Petrović also urged General Ivo Herenčić to stop killing the Serbian Orthodox clergy, who ignored him.[16] Petrović also helped to save Jews and the political dissidents, including the Yugoslav Partisans, from the persecution.[17] Even though he opposed the Ustaše regime of the Independent State of Croatia, in December 1941 he told in a conversation with Ante Ciliga, that there cannot be any state union with the Serbs.[10]

The Partisan 8th Corps entering Mostar

On 3 July 1943, he was elected Provincial of the Franciscan Province of Herzegovina.[8]

The communist Yugoslav Partisans saw Herzegovinian Franciscans as a threat to the spread of communism in Yugoslavia, as they were influential among the peasants as well as intellectuals who studied at the Franciscan schools.[18] With the Germans retreating, the Partisans with the 8th Corps, started advancing towards Mostar in January 1945.[19] Somewhere around that time, the Partisan leadership decided in Trebinje to execute all the Franciscans of the Franciscan friary in Široki Brijeg,[18] which they did, murdering 12 priests on 7 February 1945.[20] Their murderous campaign against the Franciscans continued. The next day, the Partisans murdered 8 other Franciscans who returned to the friary they previously fled,[21] as well as 5 Franciscans who hid in Mostarski Gradac, who were murdered together with the parson of Mostarski Gradac on 8 February.[22] As they advanced, the Partisans murdered three other Franciscans in Izbično on 12 February. They finally reached Mostar on 14 February. Petrović was murdered with other six Franciscans from the Franciscan friary in Mostar by being shot and thrown in the Neretva river.[9][23][24] In total, the Partisans murdered 66 Herzegovinian Franciscans.[25]