The main topic of my dissertation is the Treaty of London of April 26 1915 and its post-war consequences for Slovenian territory. Rapid technological development, the industrial revolution, the construction of railways, which consequently enabled faster and greater mobility, were perceived by the period before the First World War. The era of technological boom and the belief that the bloodthirstiness of the medieval, Napoleonic and other bloody wars would never happen again reached a boiling point on St. Vitus Day on June 28, 1914, when Gavrilo Princip assassinated Crown Prince Franz Ferdinand and his wife Sofia in the middle of Sarajevo. An event which led to the beginning of the First World War that ended the so-called 100 years of peace period. The inhabitants of now Slovenian territory, under the yoke of the Austro-Hungarian rule, were to fight a war for a foreign army against a foreign army in foreign lands. Though people’s opinion quickly changed as Italy entered the war and opened more than 600 km long battlefront towards Austro-Hungary, section of which was also fought around Soča river and thus named the Isonzo front, a front where people suddenly feared for their own land. In order to understand what led to the conclusion of the London Secret Agreement, which the Entente member states signed with Italy in 1915 when it was still officially a member of the Central Powers I will first introduce the European-wide circumstances that led to the signing of the agreements and then present the essential content of the agreement which directly concerned the Slovenian territory. The central part of the paper will focus on the analysis of the Italian occupation of territory inhabited by Slovenes after the First World War, the state of Slovene psyche under their regime and their rebellion against the ruling authorities.