Đujić's emergence as a Chetnik leader in the region around Knin was rapid.
Commencing in April, the Ustaše implemented a policy of widespread incarcerations, massacres, forced emigration, and murder of Serbs within the territory they controlled.
Around this time, Đujić's Chetniks began killing and mutilating Croat civilians.
According to Italian reports, Đujić had around 300 Chetniks under his command in April, centered mainly around Knin.
The first Ustaše atrocity in the Knin area occurred on 29 May, when a group of Serbs were killed.
Around the same time, a group of Ustaše surrounded Strmica with the aim of capturing Đujić, but he was forewarned and escaped to Kistanje in Zone I where he sought Italian protection.
Between late May and 27 July, the Ustaše killed more than 500 Serbs in the Knin district.
On 13 July, the Ustaše had ordered the arrest of all Serbian Orthodox priests in the district and the confiscation of their property, but Đujić was already beyond their reach.
While they generally stood by as the Ustaše committed atrocities, the Italians also opened up the border crossings into the Governorate of Dalmatia to Serbs fleeing the Ustaše.
Refugees from Knin and nearby regions were taken into Italian-run camps located in Split, Obrovac, Benkovac, Kistanje and Šibenik.
Đujić was a principal organiser within the Kistanje camp, which held around 1,500 refugees, and from mid-July was recruiting them for the Chetnik cause.

In August, once a general uprising against the Ustaše had begun, Đujić went to the centre of the revolt in Drvar with another Chetnik leader and sought approval from the leadership of the uprising to take leadership of the rebellion in the Knin region.
Đujić then established his Chetniks around Knin and coordinated with Chetniks in the Bosansko Grahovo district.
Đujić's Chetniks successfully kept the Ustaše out of Knin and its surroundings, sparing the local Serb population from further massacres.
As summer approached, Đujić's Chetniks captured Drvar from the Ustaše.
By early summer, he and Chetnik commander Stevo Rađenović had contacted the Italians and asked them to put a halt to the Ustaše mistreatment of Serbs, enable the return of Serb refugees, and repeal a decree that enabled the confiscation of Serb-owned property in the NDH.
The Italians obliged in the hope that doing so would win the Chetniks over to collaboration and seriously weaken any future uprising in the area, which would have further disrupted rail traffic along the Split–Karlovac railway line.
On 13 August, at a meeting in the village of Pađene northwest of Knin, Đujić and several other Serb nationalists agreed to collaborate with the Italians.
They secretly signed a pact of non-aggression with the Italian military, and in exchange, the Italians approved Đujić raising a force of up to 3,000 Chetniks.
On 31 August, at a Drvar assembly, Đujić was given the task of stopping the Italian advance on the town.
Immediately afterwards, he made an agreement with the Italians granting them free passage.
Recruiting for Chetnik formations in the region was assisted by the so-called leftist errors of the Partisans, which drove undecided Serbs to join the Chetniks.
Đujić's emergence as a Chetnik leader in the region around Knin was rapid. Commencing in April, the Ustaše implemented a policy of widespread incarcerations, massacres, forced emigration, and murder of Serbs within the territory they controlled. Around this time, Đujić's Chetniks began killing and mutilating Croat civilians. According to Italian reports, Đujić had around 300 Chetniks under his command in April, centered mainly around Knin. The first Ustaše atrocity in the Knin area occurred on 29 May, when a group of Serbs were killed. Around the same time, a group of Ustaše surrounded Strmica with the aim of capturing Đujić, but he was forewarned and escaped to Kistanje in Zone I where he sought Italian protection. Between late May and 27 July, the Ustaše killed more than 500 Serbs in the Knin district. On 13 July, the Ustaše had ordered the arrest of all Serbian Orthodox priests in the district and the confiscation of their property, but Đujić was already beyond their reach. While they generally stood by as the Ustaše committed atrocities, the Italians also opened up the border crossings into the Governorate of Dalmatia to Serbs fleeing the Ustaše. Refugees from Knin and nearby regions were taken into Italian-run camps located in Split, Obrovac, Benkovac, Kistanje and Šibenik. Đujić was a principal organiser within the Kistanje camp, which held around 1,500 refugees, and from mid-July was recruiting them for the Chetnik cause.
In August, once a general uprising against the Ustaše had begun, Đujić went to the centre of the revolt in Drvar with another Chetnik leader and sought approval from the leadership of the uprising to take leadership of the rebellion in the Knin region. Đujić then established his Chetniks around Knin and coordinated with Chetniks in the Bosansko Grahovo district. Đujić's Chetniks successfully kept the Ustaše out of Knin and its surroundings, sparing the local Serb population from further massacres. As summer approached, Đujić's Chetniks captured Drvar from the Ustaše. By early summer, he and Chetnik commander Stevo Rađenović had contacted the Italians and asked them to put a halt to the Ustaše mistreatment of Serbs, enable the return of Serb refugees, and repeal a decree that enabled the confiscation of Serb-owned property in the NDH. The Italians obliged in the hope that doing so would win the Chetniks over to collaboration and seriously weaken any future uprising in the area, which would have further disrupted rail traffic along the Split–Karlovac railway line. On 13 August, at a meeting in the village of Pađene northwest of Knin, Đujić and several other Serb nationalists agreed to collaborate with the Italians. They secretly signed a pact of non-aggression with the Italian military, and in exchange, the Italians approved Đujić raising a force of up to 3,000 Chetniks. On 31 August, at a Drvar assembly, Đujić was given the task of stopping the Italian advance on the town. Immediately afterwards, he made an agreement with the Italians granting them free passage. Recruiting for Chetnik formations in the region was assisted by the so-called leftist errors of the Partisans, which drove undecided Serbs to join the Chetniks.
Momčilo Đujić