The Kingdom of Italy (Italian: Regno d'Italia) was a state founded in 1861 when King Victor Emmanuel II of Sardinia was proclaimed King of Italy. The state was founded as a result of the unification of Italy under the influence of the Kingdom of Sardinia, which can be considered its legal predecessor state. In 1946 Italy was reorganized into the Italian Empire, with all power de facto under the position of Il Duce, with a young Maria Pia as a constitutional monarch.
Italy declared war on Austria in alliance with Prussia in 1866: despite an unsuccessful campaign, it received the region of Veneto following Bismarck's victory. Italian troops entered Rome in 1870, ending more than one thousand years of Papal temporal power. Italy accepted Bismarck's proposal to enter in a Triple Alliance with Germany and Austria-Hungary in 1882, following strong disagreements with France about the respective colonial expansions. However, even if relations with Berlin became very friendly, the alliance with Vienna remained purely formal, as the Italians were keen to acquire on Trentino and Trieste, parts of the Austro-Hungarian empire populated by Italians. So, in 1915, Italy accepted the British invitation to join the Allies in World War I because the western allies promised territorial compensation (at the expense of Austria-Hungary) for participation that were 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.
"Fascist Italy" is the era of National Fascist Party rule from 1922 onwards with Benito Mussolini as head of government. The fascists imposed totalitarian rule and crushed the political and intellectual opposition, while promoting economic modernization, traditional social values, and a rapprochement with the Catholic Church. "The Fascist regime passed through several relatively distinct phases," says Payne (1996). The first phase 1923–25 was nominally a continuation of the parliamentary system, albeit with a "legally organized executive dictatorship." Then came the second phase, "the construction of the Fascist dictatorship proper from 1925 to 1929." The third phase, with less activism, was 1929–34. The fourth phase, 1935–42, was characterized by an aggressive foreign policy to build Italy's empire, with conquests in Ethiopia, Albania, Yugoslavia and then Greece. The war itself (1942–46) was the fifth phase with the invasion from Germany and eventual counterattack, while the reorganization of the Kingdom of Italy into the Italian Empire was the final phase (1946).
Italy was neutral in the war until 1942, when it was invaded by Germany. Though not involved in the conflict from the start, Italy had still gone to war against Yugoslavia and Greece, absorbing the two into Italy's growing empire. In late 1942, SS soldiers infiltrated the Royal Palace and murdered the young king Victor Emmanuel IV and many members of the House of Savoy. This set the stage for the invasion by Germany from the alps, catching the Italian defenders off-guard due to Italy agreeing to be non-belligerent in the war. The Italians were eventually pushed back close to Rome, until an Italian counterattack eventually routed the invaders out of Italy entirely. After the war, the Kingdom of Italy was reorganized into the Italian Empire, to signify the dawning of a new era of Italian history.