The Italian Schism

The Italian Schism was a brief conflict lasting from 1538 to 1539 (Episode XV of Varna), during which Lombardy and their allies invaded the State of the Church, to depose the antipope, Gennarus I, and reinstate Pope Clement VII.
== Background ==
In April 1536, Lombardy announced to Italy that Clement had survived the Italic Sack of Roma, and spent the next year preparing for a military expedition to Roma. The ulterior goal was to retrieve a box which had been hidden by Clement during the Sack, the same box which had been discovered by Lorenzo Furlan in 1523, which contained the all-important information needed to denounce Italia for their part in staging Venice's death.
== The Invasion ==
Exactly two years later, Lombardy, Brescia, Prato and Pisa all declared war on Gennarus' Papacy, which received minor support from the Italic Union, but it was no use. The journey from Siena to Grosseto was an easy one under the leadership of Lombard General Bruno Morosini, and Prato and Pisa united with Florence and Siena to form the Tuscan Federation. From Grosseto to Roma, the invasion force was joined by Papal troops who defected to their cause. Bruno personally led the Lombard First Army into the Vatican Library, where they were joined by the Pontificial Swiss Guard. Gennarus had already been killed, but Bruno found the box empty. 
== The Treaty of Roma ==
The conflict was concluded in the Treaty of Roma, the terms of which were as follows:
# Clement VII shall be universally recognised as the Bishop of Rome and the Supreme Pontiff of the Catholic Church.
# Gennarus I shall be universally recognised as an antipope, and his pontificate between 1527-1538 declared null and void.
# All Papal cardinals from the Italic Union shall be removed and replaced.
# The complete independence and unconditional neutrality of the State of the Church shall be guaranteed by Lombardy, Brescia and Tuscany.
The treaty was signed on January 10th, 1539, allowing Italia to refocus their efforts on the succession war.