Though popular with the peasants, the Bulgarian Agrarian National Union antagonized the middle class and military, leading to a progressively more fragile position for the government.

[7][8] After being arrested and held for several weeks over falsified documents, Kolarov arrived in Sofia in early August, followed by another Comintern functionary, Alexander Abramovich.

[9] Already on 6 August, a military-technical committee was created to prepare for the uprising: the country was divided into 5 districts with distinct organizations, and plans for sabotage and guerrilla actions were being developed.

Georgi Dimitrov was tasked with attracting factions outside the BCP to participate in the uprising, but especially as the BZNS had been weaked into impotence, the practical outcome of these contact attempts were insignificant.

[10] In the following weeks, rumors about the uprising being prepared by the communists became widespread, and on 10 September, Dimitrov was forced to deny them in his article in the party's official publication, the Workers' Gazette.

[11] However, on 12 September, martial law was imposed throughout the country and around 2,000 party activists were arrested, but at the same time orders were received from the Comintern to immediately proceed with open anti-government actions.

Its leadership was assigned to the Main Military-Technical Committee, which, in addition to Kolarov and Dimitrov, included BCP Vratsa leader Gavril Genov and farmer Nikola Aganski.

[13] The leaders of the uprising, Georgi Dimitrov and Vasil Kolarov, chose northwestern Bulgaria as the staging ground - an area closer to the border with Yugoslavia.

[15] Civilian volunteers were enlisted to fight against the insurgents, later referred to as "sphitskomandi" - the name originating from the sharp tips of the shoes - type "shipts" - that they wore.

The Communist rebels were aided by an artillery unit under the command of Andrei Ivanov, an Orthodox priest turned revolutionary, but it failed to tip the scales in their favor.

On the morning of that day, under the leadership of Gavril Genov, the insurgents attacked military reinforcements heading to put down the uprising in the town of Boychinovtsi, near Ferdinand, and in the ensuing Battle of Boychin scored a major victory against government forces.

Battered and demoralized, the insurgents failed to capture the desired objectives, while heavily armored reinforcements were being deployed by the government in the direction of Ferdinand and Berkovitsa.

This was partly due to the Sofia chapter of the BCP being highly skeptical of the uprising's potential, with party leader Dimitar Blagoev stating Bulgaria was not yet ready for revolution.

By 28 and 29 September, only sporadic fighting took place between the retreating insurgents and the army, and all previously occupied villages and towns were brought back under government control.

In parts of the country, even the communists themselves did not welcome the idea of an uprising with enthusiasm,[23] and armed actions did not occur in the big cities - Sofia, Varna, Burgas, Plovdiv - where most of the supporters of the BCP are concentrated.

In the memoirs of Veselin Branev, the following story is described: Colonel Boris Brakalov, a hero of the Balkan wars, a man with left-wing ideas, who found out about the uprising being prepared, at a meeting with Dimitrov and Kolarov offered to go over to their side with all the military units he commanded.

[24] The railways of the country, in which some of the biggest strikes broke out in the previous years, functioned uninterrupted during the uprising, led by the Social Democratic Minister Dimo Kazasov.

[27] Most were massacred by paramilitary groups, including refugees from the Bolshevik regime in Russia, and in some cases the violence was motivated by personal vendettas and political conflicts not directly related to the rebellion.

Mass shootings were carried out in Gorna Gnoinica, Varshets, Berkovitsa, and Ferdinand, including a large number of militarily mobilized insurgents, while many of the organizers and leaders fled to Yugoslavia.

In a detailed documentary study published in the Communist period by the Museum of the Revolutionary Movement in Bulgaria (part of "Звезди във вековете" ("Stars in the Ages"), a named album with photographs and biographical data), 841 insurgents died in the uprising and the repressions that followed it.

[29] The failure of the September Uprising dealt a heavy blow to the Bulgarian Communist Party, which turned from a second parliamentary force into a marginal but highly radicalized group.

[30] The September Uprising gave the government of Alexander Tsankov the opportunity to present itself to the West as a fighter against the communist threat, and to plead for the easing of some of the military restrictions imposed on Bulgaria by the Treaty of Neuilly-sur-Seine.

They characterize these events as the September Riots based on studies and documents related to the organization, character, leadership, scale of the actions, their results, mass and popular support.

[31] French writers Henri Barbusse and Romain Rolland and lawyer Marcel Villard wrote books and articles in defense of the victims of the uprising.

These two writers, alongside Angel Karaliychev, author of the book of short stories "Rye", and Georgi Tsanev, were dubbed the "September Four", a prominent group that introduced leftist ideas to the Bulgarian literature of the interwar period.