Italian invasion of France in the context of "Italian declaration of war on the United States"

Imperialism, colonialism and irredentism played an important role in the foreign policy of Fascist Italy. These included both ethnic-nationalist irredentist claims and frivolous foreign adventures intended to artificially raise the regime’s prestige. Among the regime's goals were the acquisition of territory considered historically Italian in France (e.g. Nice) and Yugoslavia (e.g. Dalmatia), the expansion of Italy's sphere of influence into the Balkans (e.g. Greece) and the acquisition of more colonies in Africa. The pacification of Libya (1923–32), the invasion of Ethiopia (1935–36), the invasion of Albania (1939), the invasion of France (1940), the invasion of Greece (1940–41) and the invasion of Yugoslavia (1941) were all undertaken in part to add to Italy's national space. According to historian Patrick Bernhard, Fascist Italian imperialism under Benito Mussolini, particularly in Africa, served as a model for the much more famous expansionism of Nazi Germany in Eastern Europe.

Italy entered World War II on 10 June 1940 by invading France, joining the German offensive already in progress. Italian dictator Benito Mussolini did so opportunistically as the Allied powers (chiefly France and the United Kingdom) seemed on the verge of collapse. The Italian war aim was to expand its colonial empire at the expense of the French and the British. While France surrendered on 22 June 1940, the United Kingdom and its allies continued to fight far beyond the point which Mussolini had thought possible, ultimately leading to the defeat and dissolution of Fascist Italy in 1943 when Mussolini was deposed in a bloodless coup d'état.

Italy's Axis partner, Nazi Germany, was ready for its defection and occupied central and northern Italy after the armistice of Cassibile in September 1943. After freeing Mussolini from captivity, the Germans set him up as the leader of a new puppet state in the north, the Italian Social Republic. This provoked Italian resistance against the German occupation and also a civil war between pro- and anti-fascist Italians. In the Allied-held south, the Kingdom of Italy officially became a co-belligerent of the Allies and declared war on Germany on 13 October 1943.

The Greco-Italian War, also called the Italo-Greek War, took place between Italy and Greece from 28 October 1940 to 23 April 1941. This conflict began the Balkans campaign of World War II between the Axis powers and the Allies, and eventually turned into the Battle of Greece with British and German involvement. On 10 June 1940, Italy declared war on France and the United Kingdom. By September 1940, the Italians had invaded France, British Somaliland and Egypt. This was followed by a hostile press campaign in Italy against Greece, accused of being a British ally. A number of provocations culminated in the sinking of the Greek light cruiser Elli by the Italians on 15 August. On 28 October, Mussolini issued an ultimatum to Greece demanding the cession of Greek territory, which the Prime Minister of Greece, Ioannis Metaxas, rejected.

Italy's invasion of Greece, launched with the divisions of the Royal Army based in Italian-controlled Albania, badly armed and poorly commanded, resulted in a setback: the Italian forces encountered unexpectedly tenacious resistance by the Hellenic Army and penetrated only a few kilometers into Greek territory and had to contend with the mountainous and muddy terrain on the Albanian–Greek border. With British air and material support, the Greeks stopped the Italian invasion just inside Greek territory by mid-November and subsequently counter-attacked with the bulk of their mobilized army to push the Italians back into Albania – an advance which culminated in the Capture of Klisura Pass in January 1941, a few dozen kilometers inside the Albanian border. The defeat of the Italian invasion and the Greek counter-offensive of 1940 have been called the "first Axis setback of the entire war" by Mark Mazower.

Umberto II (Italian: Umberto Nicola Tommaso Giovanni Maria di Savoia; 15 September 1904 – 18 March 1983) was the last king of Italy. Umberto's reign lasted for 34 days, from 9 May 1946 until his formal deposition on 12 June 1946, although he had been the de facto head of state since 1944. Due to his short reign, he was nicknamed the May King (Italian: Re di maggio).

Umberto was the third child and only son among the five children of Victor Emmanuel III and Elena of Montenegro. As heir apparent to the throne, he received a customary military education and pursued a military career afterwards. In 1940, he commanded an army group during the brief Italian invasion of France shortly before the French capitulation. In 1942, he was promoted to Marshal of Italy but was otherwise inactive as an army commander during much of World War II. Umberto turned against the war following Italian defeats at Stalingrad and El Alamein, and tacitly supported the ouster of Benito Mussolini.