The conflict on Ban Jelačić Square in Zagreb, where soldiers were killed, occurred on December 5, 1918 [1] [2] [3]. This event, often referred to as the "December Victims" (Prosinačke žrtve), involved a confrontation between members of the Royal Croatian Home Guard (25th and 53rd Infantry Regiments) and the Narodna Straža (People's Guard) and Sokol volunteers, four days after the proclamation of the Kingdom of Serbs, Croats, and Slovenes [1] [2].

According to www.iAsk.Ai - Ask AI:

The background to this event was a period of significant political and social unrest following the collapse of the Austro-Hungarian Empire at the end of World War I [1]. The National Council of Slovenes, Croats, and Serbs, based in Zagreb, had declared the State of Slovenes, Croats, and Serbs on October 29, 1918, with the aim of uniting with the Kingdom of Serbia [1]. However, there were differing views on the nature of this union, with some advocating for a federal system and others for a more centralized state [1].

On December 5, 1918, a prayer service (Te Deum) was held at Zagreb Cathedral to celebrate the establishment of the Kingdom of Serbs, Croats, and Slovenes [1]. In the afternoon, a portion of soldiers from the 53rd Regiment left their barracks and marched towards Ban Jelačić Square, joined by members of the 25th Regiment and civilians [1] [2]. These soldiers carried rifles and two machine guns, accompanied by a military band [1]. Their intention was to proclaim a free Croatian republic, and they were provoked by the celebrations of the union [1] [2] [3]. They chanted slogans such as "Long live the republic!", "Long live Radić!", "Down with King Peter!", "Down with the dynasty!", "Long live the peasant party!", "Down with militarism!", "Long live the Croatian republic!", and "Long live the Bolshevik republic!" [1] [3]. Some sources also indicate they demanded the release of General Lipošćak [1].

The authorities were aware of the planned protest by 11:30 AM on the day of the event and had cleared people from the square before the soldiers arrived [1]. Armed members of the Narodna Straža and Sokol volunteers were positioned in surrounding buildings [1]. Short negotiations took place, but an armed conflict ensued [1]. Witnesses reported that machine guns were positioned by both sides [1] [3]. The conflict ended around 3:00 PM [1].

Eighteen people died in the shooting or from their injuries [1]. Among the deceased were two members of the Narodna Straža, an unidentified Serbian soldier, and two civilians [1]. Other sources state that 13 people were killed (9 soldiers) and 17 wounded [2] [3]. The deceased soldiers and civilians were later referred to as the "December Victims" [1] [2] [3].

In the evening of December 5, the National Council disbanded the 25th and 53rd Regiments, citing the incident and the Lipošćak affair as reasons to limit the inclusion of former Austro-Hungarian Croatian officers in the new army due to unreliability [1]. On December 10, the National Council disbanded all armed units formally under its command, including all former Croatian units of the Austro-Hungarian Army and Navy, and authorized a Serbian Army mission to establish new units [1].

The events of December 5 were used by the Frankovci (a faction of the Party of Rights) to portray the creation of the common South Slavic state as a national humiliation and to foster a "culture of defeat" among Croats [1]. This contributed to the rise of the Ustaše, a far-right paramilitary group and later Nazi collaborators [1].