Between the wars he was an important leader of Chetnik veteran associations, and was known for his strong hostility to the Yugoslav Communist Party, which made him popular in conservative circles.

As president of the Chetnik Association during the 1930s, he transformed it into an aggressively partisan Serb political organisation with over half a million members.

During World War II, Pećanac collaborated with both the German military administration and their puppet government in the German-occupied territory of Serbia.

[1] Just before the Axis invasion of Yugoslavia in April 1941, the Yugoslav government provided Pećanac with funds and arms to raise guerrilla units in southern Serbia, Macedonia and Kosovo.

Pećanac joined the Serbian Chetnik Organization in 1903, and fought against the Ottoman army in several significant battles including that of Šuplja Stena (near Pčinja) and Čelopek (near Staro Nagoričane).

[7] In the First Balkan War, fought from October 1912 to May 1913, Pećanac was mobilised in the Serbian Third Army, holding the rank of sergeant in the Morava Division.

[7] During the Second Balkan War, fought from 29 June to 10 August 1913, Pećanac is believed to have been stationed at the front at Kitka on Osogovo Mountain along the Zletovska and Bregalnica rivers.

[9] In September 1916, the Serbian High Command sent then-Lieutenant Pećanac by air to Mehane (south-west of Niš in the Toplica region) to prepare a guerrilla uprising in support of a planned Allied offensive.

Rivalry quickly developed between the two leaders, mainly because Pećanac only had orders to prepare to support the planned Allied offensive, but Vojinović was conducting operations that might result in pre-emptive action by the Bulgarian occupation forces.

[11] In April 1917, Pećanac re-emerged with his guerrillas, attacking a railway station, destroying a bridge and raiding a Bulgarian village on the border.

[12] During his period in hiding, he met with the Kosovar Albanian leader Azem Galica to discuss joint actions against the occupation forces.

[14] During the 1920 Constitutional Assembly elections for the newly created Kingdom of Serbs, Croats and Slovenes, Prime Minister Nikola Pašić sent Pećanac to the Sandžak with orders to intimidate the local Muslim population in the hope of keeping the turnout low.

[23][24] Shortly before the Axis invasion of the Kingdom of Yugoslavia in April 1941, Pećanac was requested by the Yugoslav Ministry of the Army and Navy to prepare for guerrilla operations and guard the southern area of Serbia, Macedonia, and Kosovo from pro-Bulgarians and pro-Albanians rebels.

Pećanac's force remained intact after the German occupation of Serbia and supplemented its strength from Serb refugees fleeing Macedonia and Kosovo.

[28] On 27 August, Pećanac issued an open "Proclamation to the Dear People", in which he portrayed himself as a defender and protector of Serbs and called "on detachments that have been formed without his approval" to come together under his command.

He demanded that individuals hiding in the forests immediately return to their homes and that acts of sabotage against the occupiers cease or the perpetrators would face death.

In the Kopaonik region, a previously loyal subordinate of Pećanac began attacking local gendarmerie stations and clashing with armed bands of Albanian Muslims.

By the end of October, the Germans decided to stop arming the "unreliable" elements within Pećanac's Chetniks, and attached the remainder to their other Serbian auxiliary forces.

[30] On November 16, German occupier held a meeting in Niš between representatives of Nedić's government and prominent Albanian collaborators from Kosovo to stop continuation of ethnic and religious violence between collaborationist groups.

[31] On 7 October 1941, Pećanac sent a request to Milan Nedić, the head of the Serbian puppet government, for stronger organisation, supplies, arms, salary funds, and more.

This fell short of the maximum authorised size of 8,745 men and included two or three thousand of Mihailović's Chetniks who were legalised in November 1941.

These orders also required the deployment of a German liaison officer with all detachments engaged in operations, and limited their movement outside their assigned area.