The immediate cause of the revolt was a campaign by the Royal Yugoslav Army, which was tasked with maintenance of public order in the area after the end of World War I, to register and brand draft animals for military use.
There is no evidence the party or Radić, who was in prison at the time, organised the rebellion but its members supported and participated in the revolt, and at least in some areas led it.
In the final year of the World War I, desertions from the Austro-Hungarian Army became widespread among soldiers who were conscripted in the Kingdom of Croatia-Slavonia, one of lands comprising Austria-Hungary.
[2] A decision on the unification was expedited because the SSCS National Council was increasingly fearful of unrest in the countryside, the Italian territorial claims set out in the Treaty of London and allegations the General of the Infantry Anton Lipošćak was plotting a pro-Habsburg coup.
[9] The HPSS's rise in popularity coincided with an increase of violence in Croatia-Slavonia's countryside in late 1918 and early 1919, and the 1918 protest in Zagreb suppressed by force.
[10] The government considered the HPSS's anti-militarism equal to the Bolshevism and therefore particularly dangerous as it was associated with the soldiers returning from Russian captivity in 1919, and contemporary mutinies in Maribor, Varaždin, and Osijek.
[11] This perception was mostly due to resistance to conscription of soldiers sent to fight Albanians in the Yugoslav colonisation of Kosovo and arbitrary beatings by army and gendarmerie as extrajudicial punishment.
[16] By August 27, local authorities south of Zagreb became aware of intentions to disrupt the branding campaign, and leaflets calling for resistance and promising aid from the Green Cadres appeared by the end of the month.
[21] On 2 September, a crowd of peasants from surrounding villages gathered in Veliki Grđevac in Grubišno Polje district, about 80 kilometres (50 mi) east of Zagreb.
According to Laginja's report, a peasant was killed and several were wounded in the clash before gendarmes led by Captain Janko Milčić scattered and ran away.
[14] According to Laginja, a crowd of about 400 confronted nine gendarmes in the town, forcing them to flee and hide; following this, the peasants proceeded to take weapons found in the district and municipal buildings.
[25] On 5 September, about 15 km (9.3 mi) south of Čazma, an armed crowd seized the gendarmerie station in Križ and it became the centre of the rebellion.
[26] The rebels took arms found there, cut down telegraph and telephone poles, and captured the railway station in nearby village of Novoselec.
During the following two days, the rebels took all firearms they could find in Križ, broke into municipal government buildings, and burnt pictures of King Peter I and regent Alexander found in offices.
On 7 September, a train taking army reinforcements from Zagreb to Kutina was stopped in Novoselec station, and a skirmish between the rebels and the soldiers resulted in fatalities on both sides.
The same day, the army and the gendarmerie deployed reinforcements in villages of Farkaševac and Trojstvo to the west and north of Bjelovar to intercept rumoured assistance from across the nearby Hungarian border.
[33] Also on 6 September, in the village of Psarjevo near Sveti Ivan Zelina, about 15 km (9.3 mi) north of Dugo Selo, another group of peasants fought three gendarmes.
Telephone and telegraph lines in the area were cut, municipal and district administration and courts, shops and taverns were looted, prompting the army to dispatch reinforcements by train from Zagreb to nearby Sesvete before moving on foot towards Sveti Ivan Zelina and arriving the following morning.
A local garrison of seven gendarmes and several armed citizens guarded Zlatar against peasant advances from the villages of Ladislavec and Mače until the reinforcements arrived in the morning.
[35] In the evening of 7 September, the gendarmerie reported the HPSS-led crowd had disarmed its station in Popovača, approximately 12 km (7.5 mi) south-east of Križ.
[36] Clashes also took place in villages near Sisak, where rumours peasants would come from all over Croatia to help an attack on Zagreb to rescue Radić from prison were being spread.
Beatings of peasants also became commonplace, and there was at least one killing reported in Novoselci [hr], where an elderly man disobeyed or did not hear a soldier's order to squat.
[41] Laginja submitted his report as a confidential document to the interior minister Milorad Drašković on 27 September and it remains the most detailed account of the events.
[42] In his report, Laginja said general discontent caused the rebellion, specifically the newly regulated, unfavourable rate of exchange of the Austro-Hungarian krone to dinar, recruitment of conscripts including World War I veterans, hostage-taking of families of army deserters, and reneging on the promise to deregulate tobacco planting and liquor distillation.
[44] According to Laginja, two particularly active peasant leaders in the Križ area were HPSS members Filip Lakuš, who called for the establishment of a republic with Radić as its head, and Stjepan Uroić.