Every year on March 17, Italy celebrates the anniversary of the Unification of Italy, in other words when Italy as a modern nation state was born.
Why March 17? Because on March 17, 1861, Victor Emmanuel II of Savoy, King of Sardinia and Piedmont, and one of the main promoters of the Italian independence movement, became the first King of Italy.
If the unification of Italy was (almost) completed (Veneto was still under the Hapsburg Empire, as were Trento and Trieste, while Lazio was governed by the Pope who did not want to recognize the Italian state), the Italians of the Risorgimento had not yet conquered a national identity. Out of 23 million inhabitants in the Italian peninsula in 1861, less than two million spoke Italian. A Sicilian and a Piedmontese did not understand each other and 78% of people could neither read nor write.
The idea of Italy as a nation (a people, a territory and a language) was the result of a slow process. A process initiated by an intellectual elite convinced that an Italic lineage and nation existed, and that the national identity was to be found in a common history. If Rome had unified the Italic peoples in the 1st century BC, the cities of the Middle Ages and the Renaissance, while politically divided, were united by a dense network of trade and exchanges. In addition, the Italians - said the patriots and the elites - had common roots in Greco-Roman antiquity, in the literary language (widespread from the 13th century, with variations from North to South) and in the arts, envied by all of Europe. In other words, they were united by culture (and given that the papacy ruled the Italian peninsula for a long time, the Church could also be considered an element of the Italian culture).
In 1861 however, most of those who lived within the geographical borders of Italy felt first of all Neapolitan, Piedmontese, Roman, Sicilian, etc.
After 1861, several factors contributed to the creation of a national identity, first of all compulsory education, which made Italian a common language for a large segment of the population and spread the idea of a national history; other factors included public rites and festivals, celebratory figures, the army and three more wars (Italy was fully unified at the end of World War I).
The process of a national identity continued well into the 20th century. The Italian sense of belonging was consolidated further after World War II, thanks to new media like television in the 1950s and ‘60s, sports (soccer and cycling in particular), and, no less important, culinary pride. Since the Middle Ages, recipes and ingredients we now consider part of Italy's national heritage, such as pasta and Parmigiano, had widely circulated across the peninsula. They were not considered the expression of a regional tradition (a somewhat recent invention), but common elements of the Italian gastronomic identity.