The fighting started when League members fired on the Austrian police who were attempting to enter the Social Democrats' party headquarters in Linz to search for weapons.

In the late 1920s the polarised political situation in Austria was exacerbated by paramilitary units such as the Home Guard (Heimwehr) on the right and the Republican Protection League (Republikanischer Schutzbund) of the Social Democrats (SDAPÖ) on the left.

By the start of the civil war the Heimwehr were openly fascist and opposed democracy,[4] while the Republican Protection League saw itself as a protector of the Austrian Republic[5] holding the Austromarxist position on the dictatorship of the proletariat that was pro-democracy as part of the Social Democrats' party program.

Political antagonisms in Austria escalated in 1927 when members of the right-wing Front Fighters' Union (Frontkämpfervereinigung) in Schattendorf (Burgenland) shot and killed two people, including a child, during a demonstration by the Republic Protection League.

The Christian Socialists, facing pressure and violence not only from the left but also from Nazis infiltrating from Germany, were able to rule by decree on the basis of a 1917 emergency law.

In the early morning hours of 12 February 1934, when police went to search for weapons at the Linz party headquarters of the Social Democrats in the Hotel Schiff, the members of the Protection League, under their local commander Richard Bernaschek, opened fire.

A coded telegram to him from the SDAPÖ's leaders that warned him urgently against any action and instructed him to await the decision of party leadership had been intercepted by the authorities and never reached him.

In Vienna, members of the Protection League barricaded themselves in city council housing estates (Gemeindebauten), which served as symbols and strongholds for the socialist movement in Austria.

Dollfuss ordered Karl-Marx-Hof, a council housing estate, to be shelled with light artillery, endangering the lives of civilians and destroying many flats before the socialist fighters surrendered.

[1] Besides the imbalance in numbers and the Austrian Army's use of artillery, the major reason for the uprising's collapse was likely the failure of the call for a general strike to be heeded.

In the city's central districts, everything went on as quietly and regularly as usual, while in the suburbs the battle raged, and we foolishly believed the official reports that everything was already settled and done with.

Analyses by later researchers vary widely, going as high as British journalist George Eric Rowe Gedye's estimate of 2,000 dead and 5,000 wounded.

[17] According to a comprehensive 2018 study by historian Kurt Bauer, between 350 and 370 people lost their lives in the fighting – about 130 of them uninvolved civilians and 110 each among the government forces and members of the Protection League.

An emergency decree of 12 February 1934 extended the list to rebellion, so that Protection League members who had been taken prisoner while armed (estimated at 10,000)[19] could be sentenced to death.

The detention camp at Wöllersdorf, which opened in the fall of 1933 for opponents of the regime – initially mostly communists and National Socialists – also held Social Democrats after February 1934.

[23] The leadership of the SDAPÖ under Otto Bauer (the leading theoretician of Austromarxism), Julius Deutsch and others fled to Czechoslovakia on 13 February,[24] a move that the representatives of the government exploited as propaganda.

[26] The government found itself isolated domestically because the Social Democrats – above all due to the death sentences that had been carried out – turned away from the state and either called for open resistance using such means as leaflets or went into a kind of inner emigration.

With a greater passage of time it became clear that Austria's ability to resist National Socialism was decidedly weakened by the Austrian Civil War and its consequences.