On September 10, Italy declared war on the Papal States, and the Italian Army, commanded by General Raffaele Cadorna, crossed the papal frontier on 11 September and advanced slowly toward Rome, hoping that a peaceful entry could be negotiated. The Italian Army reached the Aurelian Walls on 19 September and placed Rome under a state of siege. Although the pope's tiny army was incapable of defending the city, Pius IX ordered it to put up at least a token resistance to emphasize that Italy was acquiring Rome by force and not consent. The city was captured on 20 September 1870. Rome and Latium were annexed to the Kingdom of Italy after a plebiscite held in the following October.