Why did Cavour send Piedmontese troops into Umbria and Marche in 1860?

In 1860, Cavour sent Piedmontese troops into the Papal States of Umbria and Marche primarily to regain political initiative and maintain control over the process of Italian unification.12

Following the military successes of Giuseppe Garibaldi in the south, Cavour feared that the momentum of the revolutionary, republican movement might eclipse the moderate, monarchist goals of the Piedmontese government. By intervening, Cavour aimed to achieve two strategic objectives:12

• Check Garibaldi: He sought to intercept the "hero of the two worlds" to prevent potential revolutionary excesses and ensure the unification process remained under the authority of the monarchy.1
• Diplomatic Strategy: Cavour positioned himself before European powers as a defender of law and order. Simultaneously, he assured Napoleon III that the intervention was intended to protect the remaining papal territory from further attack by Garibaldi.12

This maneuver allowed Cavour to weld the northern and southern territories into a single kingdom under Victor Emmanuel II while successfully managing the complex political risks posed by both the revolutionary democrats and foreign powers.12