Map of the Kingdom of Italy at its greatest extent in 1943
The Kingdom of Italy claimed all of the territory which covers present-day Italy and even more. The development of the Kingdom's territory progressed under Italian re-unification until 1870. The state for a long period of time did not include Trieste or Trentino-Alto Adige/Südtirol, which are Italian territories today and only annexed them in 1919. The Triple Entente promised to grant to Italy – if the state joined the Allies in World War I – several territories including former Austrian Littoral, western parts of former Duchy of Carniola, Northern Dalmazia and notably Zara, Sebenico and most of the Dalmatian islands (except Krk and Rab), according to the secret London Pact of 1915.
After the compromise was nullified under pressure of President Woodrow Wilson with the Treaty of Versailles, Italian claims on Northern Dalmazia were voided. During World War II, the Kingdom gained additional territory: it gained Corsica, Nizza and Savoia from France after its surrender in 1940, territory in Slovenia and Dalmazia from Yugoslavia after its breakup in 1941 and Monaco in 1942. After World War II, the borders of present-day Italy were founded and the Kingdom abandoned its land claims.
The Italian Empire also gained territory until the end of World War II through colonies, protectorates, military occupations and puppet states. These included Eritrea, Italian Somaliland, Libya, Ethiopia (occupied by Italy from 1936 to 1941), Albania, British Somaliland, Greece (occupied in World War II), Tunisia, Croatia (Italian and German client state in World War II), Kosovo (occupied in World War II), Montenegro (occupied in World War II) and a 46-hectare concession from China in Tientsin (see Italian concession in Tianjin).
The Kingdom of Italy was theoretically a constitutional monarchy. Executive power belonged to the monarch, as executed through appointed ministers. Two chambers of parliament restricted the monarch's power—an appointive Senate and an elective Chamber of Deputies. The kingdom's constitution was the Statuto Albertino, the former governing document of the Kingdom of Sardinia. In theory, ministers were solely responsible to the king. However, in practice it was impossible for an Italian government to stay in office without the support of Parliament.
Members of the Chamber of Deputies were elected by plurality voting system elections in uninominal districts. A candidate needed the support of 50% of those voting and of 25% of all enrolled voters to be elected on the first round of balloting. If not all seats were filled on the first ballot, a runoff was held shortly afterwards for the remaining vacancies.
After a brief multinominal experimentation in 1882, proportional representation into large, regional, multi-seat electoral constituencies was introduced after World War I. Socialists became the major party, but they were unable to form a government in a parliament split into three different factions, with Christian populists and classical liberals. Elections took place in 1919, 1921 and 1924: in this last occasion, Mussolini abolished the proportional representation replacing it with a block voting system on national bases, which gave to the Fascist Party the absolute majority of the Chamber seats.
Between 1925 and 1943, Italy was quasi-de jure Fascist dictatorship, as the constitution formally remained in effect without alteration by the Fascists, though the monarchy also formally accepted Fascist policies and Fascist institutions. Changes in politics occurred, consisting of the establishment of the Grand Council of Fascism as a government body in 1928, which took control of the government system, as well as the Chamber of Deputies being replaced with the Chamber of Fasci and Corporations as of 1939.
The monarchs of the House of Savoy who led Italy were: