The Catholic League Letters

In July 1593, France is exhausted by more than three decades of religious war. For nearly eight years, the Protestant Henry of Navarre, king of France as Henry IV since 1589, has fought the Catholic League, a coalition of Catholic princes, nobles and towns that refuses to accept him as king. Led first by Henri I, Duke of Guise, and, after his assassination in 1588, by his brother Charles, Duke of Mayenne, the League relies on Spanish military aid and papal support.

That alliance is coming apart. Rome’s backing has served both the French Catholic leaders and their Spanish ally; Pope Gregory XIV even sent troops and money to sustain their war. But by 1593, Mayenne’s circle increasingly sees papal policy as favoring Spain. Filippo Sega, the representative of Pope Clement VIII in France, is closely aligned with Spanish interests. Mayenne depends on Spain’s assistance, yet resists a settlement that would place the French crown under Spanish control and diminish his own authority.

The dispute centers on the Estates General assembled in Paris to choose a Catholic king. Philip II of Spain promotes his daughter, the Infanta Isabella Clara Eugenia, whose mother was a French princess. Her claim runs against the Salic rule excluding women and succession through the female line. One way to go around this issue is for the Infanta to marry a suitable Catholic prince. Spain first proposes Archduke Ernest of Austria as her husband, then the young Charles, Duke of Guise. In opposition to Spain's interests, Mayenne presses competing candidates, including his own son, and bargains over the conditions of any election.

In May 1593, Henry IV shocks the world by announcing that he will convert to Catholicism - offering a path to reconciliation with Vatican. For Mayenne, Henry IV's impending conversion threatens both the League’s cause and his own power: once Henry becomes Catholic, the strongest religious argument against accepting him disappears.

On 22 July, just three days before the conversion, Mayenne’s secretary, Thibault Desportes, writes two letters from Paris: one to Pietro Aldobrandini, the Pope’s nephew responsible for French affairs; the other to Girolamo Frachetta, Mayenne’s agent in Rome. In these letters, Desportes defends his master’s conduct, attacks the allies he believes have abandoned him, and explains why a truce with Henry IV may now be unavoidable. The letters reveal the divisions within the Catholic alliance at the moment Henry’s conversion threatens to undo it.

Among other things, the letters give the precise amount of money received by Henry IV for his conversion to Catholicism (500,000 écus) and provide a possible reason for Frachetta's later betrayal of Mayenne (Frachetta handed over Desportes' correspondence to the Spanish in September 1593).