[3] The first Prime Minister of Italy, Camillo Benso, Count of Cavour,[4] died soon after the proclamation of Italian national unity, leaving to his successors the solution of the knotty Venetian and Roman problems.

[2] Also, a French garrison was maintained in the city by Emperor Napoleon III in support of Pope Pius IX, who was determined not to hand over temporal power in the State of the Church.

Faced with a pressing need to defend the capital with its remaining forces, the provisional government of the newly proclaimed French Republic was clearly not in a military position to retaliate against Italy.

[9] Along with this letter, Ponza carried a list of provisions from Italian Prime Minister Giovanni Lanza, setting out ten articles as the basis of an agreement between Italy and the Holy See.

[14] Under instructions from the Italian government, which still hoped to avoid seizing the capital by force, Cadorna sent a final appeal to the Papacy later the same day for the peaceful surrender of Rome.

[16] On 18 September, Minister of War Cesare Ricotti-Magnani gave Cadorna the order to attack Rome, but informed that the Leonine City, which would be reserved for the pope, should be spared, while also advising moderation.

[19] The American consul in Rome, Maitland Armstrong, described the civilian population as unwilling to defend the pope's rule, and only two hundred people in the whole city answered the papacy's call for volunteers.

Pius IX decided that the surrender of the city would only be granted after his troops had put up enough resistance, to make it plain that the Italian takeover was achieved through force and not freely accepted.

[20] Cadorna commanded the major line of assault, while troops on the other side of the city, charged with creating a distraction, were led by General Nino Bixio.

[24] Pius, members of his entourage, and the diplomatic corps later gathered at his library, where, at around 9 am,[25] he received the news from Kanzler's chief of staff of the opening of the breach near Porta Pia.

[24] Shortly afterwards, the terms of the Act of Capitulation were presented by Cadorna and signed by Kanzler at Villa Albani,[26] by which all of Rome, excluding the Leonine City, came under control of the Royal Italian Army.

[26] The pope issued the encyclical Respicientes on 1 November, in which he proclaimed a mass excommunication of the invaders, including King Victor Emmanuel II.

[32] While these measures satisfied the international community, including the Catholic countries, Pius refused to accept the law, proclaiming himself a "prisoner in the Vatican".

[35] To commemorate the successful conclusion of the negotiations, Mussolini commissioned the Via della Conciliazione (Road of the Conciliation), which would symbolically link the Vatican City to the heart of Rome.

[37] The exclusive state financial support for the Church was also ended, and replaced by financing through a dedicated personal income tax called the otto per mille, to which other religious groups, Christian and non-Christian, also have access.