In 1946, Vittorio Emanuele III's son, Umberto II, was forced to abdicate. Italy became a republic after a referendum held on 2 June 1946, a day celebrated since as Republic Day. This was the first election in Italy allowing women to vote.[19] The Republican Constitution was approved and came into force on 1 January 1948. Under the Paris Peace Treaties of 1947, the eastern border area was lost to Yugoslavia, and, later, the free territory of Trieste was divided between the two states. Fears in the Italian electorate of a possible Communist takeover proved crucial for the first universal suffrage electoral outcome on the 18th of April 1948 when the Democrazia Cristiana, under the undisputed leadership of Alcide De Gasperi, won a resounding victory with 48 percent of the vote. In the 50s Italy became a member of the NATO alliance and an ally of the United States, which helped to revive the Italian economy through the Marshall Plan: until the 60s the country saw a period of prolonged economic growth termed the "Economic Miracle". In 1957, Italy was a signatory to the Treaties of Rome founding the European Economic Community (EEC), which became the European Union (EU) in 1993.
From the late 1960s till late 1980s the country experienced a hard economic crisis and the Years of Lead, a period characterised by widespread social conflicts and terrorist acts carried out by extra-parliamentary movements. The Years of Lead culminated in the assassination of the Christian Democracy (DC) leader Aldo Moro in 1978, bringing to an end the "Historic Compromise" between the DC and the Communist Party. In the 1980s, for the first time since 1945, two governments were led by non-Christian-Democrat premiers: a republican (Giovanni Spadolini) and a socialist (Bettino Craxi); the DC remained, however, the main force supporting the government. The Socialist Party (PSI), led by Bettino Craxi, became more and more critical of the Communists and of the Soviet Union; Craxi himself pushed in favour of US president Ronald Reagan's positioning of Pershing missiles in Italy, a move the Communists hotly contested.
From 1992 to 2009, Italy faced significant challenges, as voters, disenchanted with past political paralysis, massive government debt, extensive corruption, and organized crime's considerable influence (collectively called Tangentopoli after being uncovered by Mani pulite – "Clean hands") demanded political, economic, and ethical reforms. The scandals involved all major parties, but especially those in the government coalition: between 1992 and 1994 the DC underwent a severe crisis and was dissolved, splitting up into several pieces, while the PSI and the other governing minor parties completely dissolved. The 1994 elections put media magnate Silvio Berlusconi into the Prime Minister's seat. However, he was forced to step down in December when the Lega Nord Party withdrew its support. In April 1996, national elections led to the victory of a centre-left coalition under the leadership of Romano Prodi. Prodi's first government became the third-longest to stay in power before he narrowly lost a vote of confidence, by three votes, in October 1998. A new government was formed by Massimo D'Alema, but in April 2000 he resigned. In 2001, national elections led to the victory of a centre-right coalition under the leadership of Silvio Berlusconi, the centre-right formed a government, and Silvio Berlusconi was able to remain in power for a complete five-year mandate, but with two different governments. The first one (2001–2005) became the longest-lived government in post-war Italy. Italy participated in the US-led military coalition in Iraq. The elections in 2006 were won by the centre-left, allowing Prodi to form his second government, but in early 2008 he resigned because of the collapse of his coalition. In the ensuing new early elections in April 2008, Silvio Berlusconi convincingly won to form a government for a third time.
