An excess of political problems within Austria-Hungary itself, exacerbated by the earlier Balkan Wars, led to a state of unrest, strikes, and series of assassinations within Croatia at the outbreak of World War I. Croatian policy amounted to either trying to find the best solution whilst staying within the empire (such as Trialism in Austria-Hungary or Austro-Slavism) or unifying with Serbia and Montenegro (namely Yugoslavism), thereby forming a South Slavic state.

[3] The evening of the assassination, Croats held commemorative parades and gatherings, carrying pictures of the fallen heir to the throne and Croatian flags adorned with black flora.

After someone threw stones at the commemorative parade, the party's followers demolished Serb-owned stores and cafés, as well as the gathering places of pro-Yugoslav politicians.

[16] An extraordinary session of the Croatian Parliament, which was convened to read a loyalty oath to the Empire and statement of condolence, was interrupted with accusations and recriminations against ruling Croatian-Serbian coalition by the members of Party of Rights (HSP).

The next day, ban Iván Skerlecz issued a special regulation abrogating Ivan Mažuranić's 1875 Law on Freedom of Assembly.

[18] Since the last conflict that Croatia was involved had taken place in 1878, and since all of Europe had enjoyed almost 50 years of peace and relative stability, the war was met with shock and disbelief.

He amnestied all political prisoners after coming under strong pressure from the international public and in preparation for the conclusion of a separate peace treaty with the Triple Entente.

Most of the territory of modern-day Croatia, with the exception of Eastern Syrmia and some Dalmatian islands (Palagruža, Lastovo), was not affected by military operations, but 60,000 residents of Pula and the surrounding area were forced to relocate in 1915 to refugee camps in Austria, Bohemia and Slovenia because of the proximity of war, and the security of the naval port.

During all four years of war, Kingdom was in danger of seduction of the dictatorship of Military Commissariat which was constantly trying to seize power from the Croatian Parliament.

[21] Nevertheless, the involvement of Russian and Serbian prisoners of war, who were ascribed to agricultural estates and factories for forced labor, was helping out.

There was a shortage of products, as evident from the fact that the copper roofs of Dubrovnik Cathedral and Croatian State Archives palace were removed and warm in the ammunition.

The rings had inscription "I Gave Gold for Iron 1914" and were protected by the stamp of the Commission for the Organization of Voluntary War Nurse Service.

[24] In addition, in the year 1915, citizens of Zagreb could hammer a nail into the trunk of the lime tree at Nikola Šubić Zrinski Square for a symbolic amount of money, thus collecting resources for families of soldiers who were killed in the war.

[25] This action took place in other Croatian cities as well; in Pula donors could hammer a nail into the lighthouse, and in Jastrebarsko in wooden hawk.

Avenue of chestnut trees in the main street of Sinj, which is used as the racecourse of Sinjska alka, was planted in memory of the recruited soldiers who went to war in 1917.

Therefore, the Zagreb Central Committee for the Care of Families of Mobilized and Killed Soldiers, began a large humanitarian action of relocation of children from Istria to the north Croatia.

[27] This charity campaign was accepted by the Franciscans of Herzegovina as a lifeline for (Catholic) children, which was initiated and implemented by Fra Didak Buntić.

Sailors Koucký Frantisek (Czech) and Ljubomir Kraus (Croat) tried to escape from Pula with a torpedo boat T-80 but were betrayed, sentenced to death and executed.

In the northern Croatia, deserters from the Royal Croatian Home Guard, known as Green Cadres, were randomly looting and burning down nobility castles and estates.

Since July 1918, some Croatian troops fought on the Western Front as part of 18th Corps:[36][37] 31 hunting battalion, two squadrons of the 10th Hussar Guard Regiment[38] and artillery units in the Battle of Verdun.

Croatian gunners fought as part of the Austro-Hungarian artillery batteries in Sinai and Palestine as assistants to the Turkish forces.

[41] Intention of the General Staff was clear – Croats from Dalmatia had a motive to fight against Italy, since they were directly threatened by the Italian plans of taking the eastern Adriatic coast according to the Treaty of London.

[43] Croats that were captured on the Italian and Galician battlefields often ended up in the so-called Yugoslav Legion, where they continued to fight on the Macedonian front.

[44] Part of Croatian emigrants helped the work of the Yugoslav Committee, while others opposed its idea of creating a unified South Slavic state.

"[49] However, as the end of the war approached, he was dissatisfied with the unfavorable position of Croatia so he changed his mind, stating in September 1917 that he would be the first one to shout "Down Habsburgs!"

Vice-ban Vinko Krišković, who was tirelessly working to strengthen Croatian position within the Empire, managed to persuade the emperor to guarantee the territorial integrity of Croatia, Slavonia and Dalmatia in his inaugural oath on New Year's Eve of 1916 in Budapest.

This prevented emperor to mention otherwise agreed the text of the oath before the Imperial Council in Vienna in 1917, which stated that Dalmatia was an Austrian crown land.

[51] Representatives of Croats from Dalmatia and Istria and Slovenes, gathered in a Yugoslav parliamentary club in the Imperial Council, after the death of Emperor Franz Joseph in 1916, submitted May Declaration in which they called for reorganization of the Empire on the trialist principles.

Anton Korošec (Slovene) was Council president, with vice-presidents being Ante Pavelić Sr. (Croat) and Svetozar Pribićević (Serb).

Italian occupation of Dalmatia has prompted the government to seek unification with Serbia as soon as possible in order to get protection since their state did not have standing army.