How did the revolutions in Tuscany, Parma, Modena, and Romagna assist Italian unification?

The revolutions in Tuscany, Parma, Modena, and the Papal Legations (Romagna) were pivotal in advancing Italian unification by creating a "revolutionary landslide" that proved impossible to reverse.12

Following the outbreak of the war of 1859, these regions rose up against their rulers, leading to the expulsion of the grand duke of Tuscany and the ducal rulers of Parma and Modena, as well as the removal of papal legates. These events significantly assisted the cause of unification in several ways:12

• Popular Mandate: The liberated states held plebiscites that overwhelmingly expressed a desire for union with Piedmont, providing a clear popular mandate for annexation.13
• Diplomatic Pressure: Although Napoleon III initially agreed at the Conference of Villafranca to restore the deposed rulers, the persistence of the revolutionary movements and the support of Britain for a strong Italian state forced him to reconsider.1
• Cavour’s Strategy: These developments ultimately strengthened the hand of Camillo Benso, count di Cavour, allowing him to return to office and successfully pursue the annexation of these territories, which served as a crucial step toward the formation of a unified Kingdom of Italy.12