A/ The first period (the end of July 1941 - February 1942
This period consists of two parts: the first, from the eruption of the rebellion until the autumn of 1941, when Chetniks and guerrillas participated in the rebellion together; and the second, which began at the same time as the division of the Chetnik and national liberation movement, namely, the division of the military into Chetniks and Partisans and crimes of Chetnik units may be observed.
In the first part, after the eruption of the revolt, in actions carried out jointly by the Chetniks and communists, the first massive crimes against Croatians and Muslims in Bosnia and Herzegovina and Croatia were carried out. In this way, on July 27, 1941 and several days afterwards, in Bosansko Grahovo and the surrounding area, 62 Croatians, among whom were five women, nine children, and parish rector Ante Gospodnetic were killed by the rebels while their houses and five villages were burned after being looted. On July 2, in Krenjus and its surrounds, as well as in Vrtoci, several hundred Croatians, the majority being older individuals, women and children and the parish rector Kresimir Baric were massacred. They looted and burned houses and the Roman Catholic Church. Then followed the arrival of 2,500 Croatians from Boricevac and the surrounding area into Bihac. Boricevac itself was looted and completely burned and never rebuilt after the war. As a result, 19 Roman Catholic parishes on the right side of the Una River and ten on the left shore ceased to exist since there was no congregation left. Subsequently, on September 5, 1941, in Kulen Vakuf, 3,000 Muslims and a hundred Croatians were slaughtered and the area was looted and burnt. Also, 44 Muslims and 12 Croatians were killed in Varcar Vakuf and the surrounding areas. In Glamoc and its surrounds, 45 Muslims and two Croatians were killed. In Sanski Most the rebels "killed Muslims and Croatian peasants and even their families: women and."17
It was the same in other areas. In this way, the "liberated territories" were soon liberated from Croatians and Muslims who were forced to leave so as not be slaughtered and killed. Their houses and villages were looted and burned. Soon, a river of 50,000 refugees began to flow into Bihac, Jajce, Knin, Sanski Most, Prijedor, Livno, and other towns. The share the Chetniks and their supporters took in executing these crimes was dominant. In eastern Herzegovina, massacres of civilians were carried by out rebels with assistance from Montenegro and this in Avtovac on June 28, 1941 when some 47 Muslims were massacred; in Berkovici (Dabar) on August 28, 300 Muslims were massacred, predominantly women and children, who were thrown into pits, and the majority into the "Cavkarica" pit, according to Partisan documents. According to the documents of NDH authorities, the number is considerably greater. Some Croatians were killed, while from the entire eastern Herzegovina region, colonies of refugees, flowed into neighbouring towns, predominantly Capljina, Mostar, and Dubrovnik. After being looted, many houses and villages were burned. It was in eastern Bosnia, where Chetnik units, established and assisted by Chetniks in Serbia, and active since the beginning of the revolt, that the first massacres of Muslims were recorded and this in Medjedja and Koraj in October and November 1941. Several hundred people were slaughtered.18
Since the NDH powers were unable to suppress the rebellion and hinder its spreading, Italian and German occupying forces intervened. The Italians occupied Zones I and II and the Germans brought in new forces. The Italians enabled the organization and supplies for the Chetnik units and their close links from Serbia to Slovenia, who in turn organized, planned, and commenced the genocidal crimes against Croatians and Muslims. In this way, Chetniks around Knin and at the three border point started the terror against the Croatian population. On October 7 and 8, 1941, they slaughtered seven Croatians in Donji Ervenik. On July 3, 1941, they ordered "that all Catholics in the village of Stikova be converted to the Orthodox faith." In an attack 16 days later, 11 local Croatians and 1 gendarme were killed. On December 11, in the village of Velika Plana, by Lovinac, six Croatians were massacred and before that, on September 29, 1941, 44 Croatians of Brotinja by D. Lapac were captured and then slaughtered. The majority were women and children. This resulted in a new wave of Croatian refugees.