In 1417, when he was elected, Pope Martin was living in Florence where a banker named Giovanni de’ Medici was immediately keen to win his favour. Already rich from papal business, Medici personified the rising prosperity of Florence, a landlocked Tuscan city state, a republic ruled by the
Giovanni changed that. Florentines were experts in refining, dyeing and exporting wool shipped to them from England, Flanders and Burgundy, a trade aided by their capture of Pisa and its port, Livorno. Medici was the owner of two wool workshops, but then he expanded into the other Florentine expertise, banking,* which was aided by the widespread use through Europe of the city’s gold coins, florins. In 1401 Giovanni had played a role in commissioning the new doors of the Baptistery, a thanksgiving for Florentine emergence from a spasm of the plague, to be decided by a competition. It was jointly won by Lorenzo Ghiberti and Filippo Brunelleschi, and Giovanni then commissioned the latter to build a Medici family basilica, the San Lorenzo. Afterwards Brunelleschi created the 138-foot-diameter dome of the city cathedral, Il Duomo, which was consecrated by the pope.
Medici had become rich through his friendship with the most unlikely pope since Marozia. A Neapolitan pirate, Baldassare Cossa, had flourished in the chaos of multiple popes, murdering his predecessor, winning election as John XXIII, his papacy and wars funded by ‘my very great friend’ Medici. Often accompanied by Giovanni’s son, Cosimo, Cossa hoped to end the schism of popes but in 1414 he was deposed, accused of sodomy, piracy, murder, incest and the seduction of 200 girls. Cossa escaped but was captured and imprisoned. Medici ransomed his piratical patron, but he now backed a rising cardinal, Oddone Colonna, a Florentine monk and descendant of Marozia. Ecclesiastical potentates then elected Colonna as Martin V in order to reunite the Church. In September 1420, Martin formally processed from Florence to Rome, where he appointed Medici as papal banker assisted by his son Cosimo.
Already experienced in trading in Rome and Flanders, Cosimo, now thirty, had been educated by Florence’s humanist scholars. As the Medici became richer, their rivals in the
Just after his father’s death, an anti-Medici party on the
When his Tuscan friend and fellow bibliophile Tommaso Parentucelli was elected Pope Nicholas V, Cosimo helped fund an astonishing project: the new Rome. He opened banks all over Europe, with the slogan ‘In the Name of God and Good Business’, trading wool, spices, brocades. But much was based on the trade in alum, a mineral necessary for dyes, glassmaking and tanning. As the Ottoman advance cut off eastern supplies, alum mines were developed in the papal lands. Medici was appointed papal alum agent and alum became the windfall that funded the start of a two-century enterprise of urban regeneration: a Christian sacred city grafted on to the pagan splendour.