The unification of Italy was a movement to bring the numerous city-states that comprised the Italian peninsula together as a single unified nation. The movement began in the mid-19th century and lasted until 1870.
The idea of a united Italy began to form with the fall of Napoleon in 1814. At that time, the Italian peninsula comprised several independent city-states. The movement to unite Italy began underground and spread throughout the early part of the 19th century. The movement erupted in a series of revolts in 1848. Although those initial revolts were unsuccessful, they laid the foundations for the unification of Italy. The turning point came when the prime minister of Piedmont-Sardinia, the most affluent of the city-states, formed an alliance with France. France entered into war with the Austrian empire, which had been a key player in suppressing the movement for the unification of Italy, and won. As a result, lands belonging to the Austrian empire were granted to Piedmont-Sardinia. After that point, the rest of the city-states in the northern Italian peninsula voted to become part of Piedmont-Sardinia. Once it was united, the northern peninsula assembled an army and sent it into the southern part of the peninsula to pressure those city-states to join the united northern states. By 1861, a parliament had been formed, but it did not include Rome and Venice. Those two holdouts were taken by the Italian army in 1870, and the Italian peninsula became a unified nation.