Pazzi Conspiracy
Grievances
Quarrels with the Pope
When Lorenzo showed no inclination to contrition, Sixtus started to apply pressure. In July 1474 he ceased to do business with the Medici. In October 1474 he named Francesco Salviati to be Archbishop of Pisa. Then in December, he ordered the Medici accounts on the papal alum mines to be audited.
These actions angered both sides. The Salviati affair was particularly irksome because Florence had always had an understanding that the city's Priors should have the right to review any candidate to the archbishopric of Pisa. Sixtus deliberately ignored that tradition (which, truth be told, was less than a century old anyway).
In retaliation, the Priors ordered the gates of Pisa closed to Salviati. The man had to sit in Rome, stewing over the slight and unable to take up his office.