The Kingdom of Italy was a unitary state that existed from 17 March 1861, when Victor Emmanuel II of Sardinia was proclaimed King of Italy, until 18 June 1946, when the monarchy was abolished, following civil discontent that led to an institutional referendum on 2 June, resulting in the establishment of the modern Italian Republic. The kingdom was established through the unification of several states over a decades-long process, called the Risorgimento. That process was influenced by the Savoy-led Kingdom of Sardinia, which was one of Italy's legal predecessor states.
In 1866, Italy declared war on Austria in alliance with Prussia and, upon its victory, received the region of Veneto. Italian troops entered Rome in 1870, ending more than one thousand years of Papal temporal power. In the last two decades of the 19th century, Italy developed into a colonial power, resulting to the establishment of the Italian Empire, and in 1882 it entered into a Triple Alliance with the German Empire and the Austro-Hungarian Empire, following strong disagreements with France about their respective colonial expansions. Although relations with Berlin became very friendly, the alliance with Vienna remained purely formal, due in part to Italy's desire to acquire Trentino and Trieste from Austria-Hungary. As a result, Italy accepted the British invitation to join the Allied Powers during World War I, as the western powers promised territorial compensation (at the expense of Austria-Hungary) for participation that was more generous than Vienna's offer in exchange for Italian neutrality. Victory in the war gave Italy a permanent seat in the Council of the League of Nations, but it did not receive all the territories it was promised.
In 1922, Benito Mussolini became prime minister and the National Fascist Party took control of the Italian government, thus ushering an era of the Fascist period in Italy known as "Fascist Italy". Authoritarian rule was enforced, crushing all political opposition while promoting economic modernization, traditional values, and territorial expansion. In 1929, the Italian government reconciled with the Roman Catholic Church through the Lateran Treaties, which granted independence to the Vatican City. The following decade presided over an aggressive foreign policy, with Italy launching successful military operations against Ethiopia in 1935, Spain in 1937, and Albania in 1939. This led to economic sanctions, departure from the League of Nations, growing economic autarky, and the signing of military alliances with Germany and Japan.
Italy entered World War II as a leading member of the Axis Powers in 1940 and despite initial success, was defeated in North Africa and the Soviet Union. Allied landings in Sicily led to the fall of the Fascist regime and the new government surrendered to the Allies in September 1943. German forces occupied northern and central Italy, established the Italian Social Republic, and reappointed Mussolini as dictator. Consequentially, Italy descended into civil war, with the Italian Co-belligerent Army and resistance movement contending with the Social Republic's forces and its German allies. Shortly after the surrender of all Axis forces in Italy, civil discontent prompted an institutional referendum, which established a republic and abolished the monarchy in 1946.
The Kingdom of Italy covered and at times exceeded the land area of the successor Italian Republic. The kingdom gradually extended its area through the Italian unification until 1870. In 1919 it annexed Trieste and Trentino-Alto Adige/Südtirol. The Triple Entente promised to grant to Italy – if the state joined the Allies in World War I – several regions, including former Austrian Littoral, western parts of former Duchy of Carniola, Northern Dalmatia and notably Zara, Šibenik and most of the Dalmatian islands (except Krk and Rab), according to the secret London Pact of 1915.
After the refusal by President Woodrow Wilson to acknowledge the London Pact and the signing of the Treaty of Versailles in 1919, with the Treaty of Rapallo in 1920 Italian claims on Northern Dalmatia were abandoned. During World War II, the kingdom gained additional territory in Slovenia (province of Lubiana) and Dalmatia (Governatorate of Dalmatia) from Yugoslavia after its breakup in 1941.
Italy established and maintained until the end of World War II colonies, protectorates, military occupations and puppet states beyond its borders. These included Eritrea, Italian Somaliland, Libya, Ethiopia (annexed by Italy from 1936 to 1941), Albania (an Italian protectorate since 1939), British Somaliland, part of Greece, Corsica, southern France with Monaco, Tunisia, Kosovo and Montenegro (all territories occupied in World War II) Croatia (Italian and German client state in World War II), and a 46-hectare concession from China in Tianjin (see Italian concession in Tianjin). These foreign colonies and lands came under Italian control at different times and remained so over different periods.
The Kingdom of Italy was a constitutional monarchy. Executive power belonged to the monarch, who governed through appointed ministers. The legislative branch was a bicameral Parliament comprising an appointive Senate and an elective Chamber of Deputies. The kingdom maintained as its constitution the Statuto Albertino, the governing document of the Kingdom of Sardinia. In theory, ministers were responsible solely to the king. However, by this time, a king couldn't appoint a government of his choosing or keep it in office against the express will of Parliament.
Members of the Chamber of Deputies were elected through a plurality voting system in single-member districts. A candidate needed the support of 50% of votes and 25% of all enrolled voters to be elected in the first round of ballots. Seats not adjudicated on the first ballot, were filled through a runoff held shortly after the first ballots. In addition to this, there was a Council of State, which had consultative powers and decided on conflicts of jurisdiction between administrative authorities and courts, as well as on disputes between the state and its creditors. It consisted of a president, three section presidents, 24 councilors of state and the service staff, and was appointed by the king on the proposal of the Council of Ministers.
There was brief experimentation in 1882 with multi-member districts, and after World War I proportional representation was introduced with large, regional, multi-seat electoral constituencies. The Socialists became the major party, but were unable to form a government in a parliament split among the three factions of Socialists, Christian populists, and classical liberals. Elections took place in 1919, 1921 and 1924: on this last occasion, Mussolini abolished proportional representation, replacing it with the Acerbo Law, by which the party that won the largest share of votes got two-thirds of the seats, which gave the Fascist Party an absolute majority of the Chamber seats.
Between 1925 and 1943, Italy was a quasi-de jure fascist dictatorship, as the constitution formally remained in effect without alteration while the monarchy formally accepted Fascist policies and institutions. In 1928 the Grand Council of Fascism took control of government administration, and in 1939 the Chamber of Fasces and Corporations replaced the Chamber of Deputies.
The highest state administration was divided into the following ministries, with their headquarters in Rome:
Ministry of Foreign Affairs (with the Council for Diplomatic Disputes)
Ministry of the Interior (with the Supreme Health Council)
Ministry of Mercy, Justice and Religious Affairs
Ministry of Finance and Treasury
Ministry of War (the committees for the General Staff, the Line Arms, the Royal Carabiniers, for Artillery and Engineering, for Military Health and the Supreme War and Naval Tribunal are subordinate to it)
Ministry of the Navy (with the Supreme Navy Council)