Pope Pius V dies on May 1, 1572.

After a very brief conclave, lasting less than twenty-four hours, presumed by many historians to have been due to the influence and backing of Philip II of Spain, the successful candidate is Bologna-born Ugo Boncompagni, a respected canonist who advanced in the church's hierarchy despite his having fathered an illegitimate son before his ordination.

Having served as a legate to the Spanish King, being sent by the Pope to investigate the Cardinal of Toledo, it was there that Boncompagni had formed a lasting and close relationship with the Philip, which is to become very important during his foreign policy as Pope.

He ascends the throne on May 13 as Gregory XIII, in homage to the great reforming Pope, Gregory I (590–604), surnamed the Great.

His character seems to be perfect for the needs of the church at the time.

Unlike some of his predecessors, Gregory XIII is to lead a faultless personal life, becoming a model for his simplicity of life.

Additionally, his legal brilliance and management abilities mean that he is able to respond and deal with the major problems quickly and decisively, although not always successfully.

A third party of moderate Catholics, known as the Politiques, emerges under the family of Montmorency at the end of 1572, following the deaths of several thousand French Huguenots in what has become known as the Saint Bartholomew's Day Massacre.

Both Philip II of Spain and Pope Gregory XIII declare themselves pleased with the outcome, which is naturally viewed with horror by their religious opponents throughout Europe.

In France, it solidifies Huguenot opposition to the crown.

Stukley's exploits had restored him to favor at Madrid, and by the end of March 1572 he was at Seville, offering to hold the narrow seas against the English with a fleet of twenty ships.

He is said to have received in four years (1570-1574) over twenty-seven thousand ducats from Philip II of Spain but, wearied by the king's delays, he seeks more serious assistance from the new pope, Gregory XIII, who aspires to make his illegitimate son, Giacomo Buoncompagni, king of Ireland if the Catholic faith were to be restored to dominance there.

When his father was elected pope in March 1572, Giacomo had moved to Rome where, two months later, he had been appointed castellan of Castel Sant'Angelo.

His father had later named him also Gonfalonier of the Papal Army, and he had moved first to Ancona and then Ferrara, remaining in the latter until 1574.

Florentine native Philip Neri, who studied in Rome as a young man and also worked among the poor and sick of the city, was ordained in 1551 and becomes noted as a confessor and for bringing about a religious revival among the Romans.

Pope Gregory XIII in 1575 approves Neri’s Congregation of the Oratory, where priestly members lead a devotional life without vows.

The charismatic Neri, whose good judgment and friendly, playful disposition earn him love and respect, becomes known as the Apostle of Rome.

Italian mathematician Gerolamo Cardano, a pioneer in the study of probability, publishes one of the first modern psychological autobiographies, De vita propria liber (“Book of My Life”) in 1575.

Spanish composer Tomas Luis de Victoria, who may have studied with Bartolomé Escobedo and Palestrina, gains experience in Rome, where he first studies, as an organist and choirmaster, having competent Catholic church choirs for the performance of his works.

He enters the priesthood in 1575 but continues to compose and direct music in Rome.

Stukley allies with Fitzmaurice and moves to Rome in 1575, where he walks about the streets and churches barefoot and bare legged (which causes the lord deputy of Ireland, Sir William Fitzwilliam, to write sarcastically of his holiness, remarking that it had caused the people of Waterford, where he had put on a similar performance while awaiting favorable winds for five weeks prior to his departure, to believe in his piety).

He has an interview at Naples with Don John in June, when he gives details of the plans hatched with the pope for an October expedition.

The intention is to deliver Mary Stewart from prison and take possession of England.

He has corresponded with Nicholas Sanders at this stage.

Don John, who is now in charge of the Spanish forces in Flanders, says the king would have to approve and that three thousand men are too few, but is cautiously optimistic that the expedition would help to contain the rebellion in the Netherlands.

The prospect of a major invasion has been growing, and detailed proposals are put forward for Ireland.

Friar Patrick Healy arrives at Rome in 1575, bearing a letter from the king and announcing that he seeks sanction for an unnamed Irish gentleman to revolt and to request assistance; he insists Philip II has given his blessing.

Gregory stresses that the crown ought not to go to a French or Spanish claimant, but to a native Catholic, i.e. Mary Stewart, lest the king gain too much power and territory, and is opposed to Don John being crowned in Ireland.

The king denies O'Healy's authority to enter discussion on the Irish matter and queries the pope's opposition to the increase of Spanish authority; he is willing to guarantee six months pay for two hundred men and their shipping expenses to go to England in the pope's name, and wonders if a personal attempt might be made against Elizabeth.

Later, it is suggested that five thousand go to Liverpool and free Mary before possessing the country, or go to Ireland.

Gregory bargains for Philip II to defray the entire expense of the expedition, and suggests that if the Vatican is to pitch in then it should receive some benefit in Italy by way of material return.

The Spanish think the leader of the expedition should be married, so as to prevent papal approval of a match with Mary.

Thomas Stukely reaches Cadiz with rotted ships, where in Apri he issues magnificent passports to Irishmen returning home, describing himself as Marquess of Leinster (a title bestowed by the pope).

The Irish rebel James Fitzmaurice Fitzgerald, called Fitzmaurice, had fled in 1575 to the European continent, despite his pardon.

He had been warmly received the following year at Rome, where Father William Allen, close to Gerald Fitzgerald, 15th Earl of Desmond, was also present, having presented to the pope a plot for the invasion of England through Liverpool, with five thousand musketeers under Thomas Stukley's command.

The Geraldine connection had been made, and in 1578 Stukley is provided by the pope with infantry and sets out with two thousand men, including musketeers (or maybe swordsmen); the force has been raised by enlisting Appennine highwaymen and robbers in return for pardons and fifty-day indulgences, the latter to be gained by contemplation of crucifixes supplied to Stukley—although there are also professional officers, including the commander, Hercules of Pisano, and also Giuseppi, who will go on on to command the Smerwick garrison at the beginning of the Second Desmond Rebellion.

In sum, Stukley's ranks rise to four thousand.

Stukley sails for Ireland from Civitavecchia in March 1578.

The Portuguese Succession Crisis of 1580: The End of the Aviz Dynasty

With the death of King Henry of Portugal on January 30, 1580, the House of Aviz, which had ruled Portugal for 200 years, became extinct in the legitimate male line. Henry had renounced his clerical vows in hopes of marrying and producing an heir, but Pope Gregory XIII, aligned with the Habsburgs, refused to release him, preventing the continuation of the Portuguese royal line.

Henry’s brief reign (1578–1580) had been largely focused on raising ransom payments for Portuguese captives in Morocco following the disastrous Battle of Alcácer Quibir (1578). His failure to appoint a Council of Regency to determine a successor plunged Portugal into a succession crisis, as multiple claimants vied for the throne.

The Claimants to the Portuguese Throne

1. Ranuccio Farnese (1569–1622) – The Closest Heir by Feudal Custom

   • Closest genealogical heir, as the son of Maria of Portugal, the eldest daughter of Dom Duarte, Duke of Guimarães, who was the only son of Manuel I whose legitimate descendants survived.
   • As Duke of Parma’s son, he was a foreigner, only eleven years old, and unlikely to win Portuguese support.

2. Catherine, Duchess of Braganza (1540–1614) – A Strong Domestic Candidate

   • Second in line after her nephew Ranuccio, being the younger daughter of Dom Duarte.
   • Married to John I, Duke of Braganza, a descendant of King Duarte I, reinforcing her dynastic legitimacy.
   • Her son, Teodósio de Braganza, would inherit the crown, ensuring a Portuguese royal future.
   • Advantages:
     • Resided in Portugal, unlike Ranuccio.
     • Was an adult, not a child.
     • Supported by nobles who wished to keep Portugal independent.
   • Disadvantages:
     • Her gender, as Portugal had never had a generally recognized ruling queen.
     • Was the younger daughter, meaning her claim was weaker than that of her nephew, Ranuccio.

3. Philip II of Spain (1527–1598) – The Habsburg Claimant

   • Grandson of Manuel I through his mother, Isabella of Portugal, making him next in line after Ranuccio and Catherine.
   • Strongest military power, with Spanish troops ready to enforce his claim.
   • Advantages:
     • Had overwhelming military and political strength.
     • Backed by Pope Gregory XIII, the Jesuits, and pro-Spanish nobles.
   • Disadvantages:
     • Seen as a foreigner, which fueled Portuguese resistance to his rule.
     • Only claimed through a female line, unlike António.

4. António, Prior of Crato (1531–1595) – The Nationalist Challenger

   • Grandson of Manuel I in the male line, but illegitimate, as his father, Prince Louis, had not been officially married at the time of his birth.
   • Appealed to national sentiment, presenting himself as a new John I of Portugal, invoking the 1383–1385 crisis, when an illegitimate Aviz prince took the throne.
   • Supported by the lower classes, clergy, and those opposed to Spanish rule, but lacked noble backing.

The Political Struggle: Who Would Rule Portugal?

• Portugal’s nobility and clergy feared Spanish dominance, but many were reluctant to support a female ruler (Catherine) or an illegitimate one (António).
• Philip II, with Spanish military power, was the most formidable contender, despite being foreign-born.
• António of Crato attempted to rally nationalist support, but failed to secure noble backing.

By June 1580, the succession crisis erupted into open conflict, leading to the Iberian Union under Philip II and sixty years of Spanish rule (1580–1640).

Conclusion: The Fall of the Aviz Dynasty and Portugal’s Fate

With no clear and universally accepted Portuguese heir, Philip II of Spain successfully claimed the throne, leading to the Iberian Union (1580–1640). Although Portugal remained administratively separate, it was effectively under Spanish control. However, the succession crisis and foreign rule fueled long-term resentment, setting the stage for Portugal’s eventual Restoration War (1640–1668) and its return to independence under the House of Braganza.

Vittoria Accoramboni, renowned for her beauty, intelligence, and sweet temper, had been the tenth child in a well-to-do but not illustrious family that had hoped to better its position by marrying Vittoria to an influential man.

In 1573 she had been married to Francesco Peretti, probably because his uncle, Cardinal di Montalto (Felice Peretti), was regarded as likely to become pope.

Through the help of Peretti, Vittoria's brother Marcello had become chamberlain to the powerful Duke di Bracciano (Paolo Giordano Orsini), who is known to have murdered his wife Isabella de' Medici because of her infidelity.

Marcello hopes to get the duke interested in his sister, and, when it becomes evident that Bracciano is infatuated with her, Marcello—possibly on his own or possibly with the aid of the duke—has Peretti murdered in 1581.

Vittoria marries Bracciano soon thereafter in a private ceremony, but, because of the opposition of Pope Gregory XIII, Vittoria is imprisoned for a while.

She is released, untried, because of public pressure.

The Corpus Juris Canonici, or Corpus of Canon Law, a set of six compilations of law in the Roman Catholic Church that provides the chief source of ecclesiastical legislation from the Middle Ages, includes four official collections: the Decretum Gratiani (“Decree of Gratian”), written between 1141 and 1150; the Decretals of Pope Gregory IX (1234); the Liber Sextus (“Book Six”) of Pope Boniface VIII (1298); and the Clementinae of Pope Clement V (1317); and two private collections: the Extravagantes of Pope John XXII (1325) and the Extravagantes communes (“Decretals Commonly Circulating”)—the decretals, or replies of the pope to particular questions of church discipline, from Pope Boniface VIII to Pope Sixtus IV—both of which had been compiled at the beginning of the sixteenth century by Jean Chappuis, a canonist at the University of Paris.

The title Corpus Juris Canonici had first been applied to the six collections by Pope Gregory XIII in the document Cum pro munere (1580), which approved an edition of the works as textually authentic.

These collections do not form a closed body of ecclesiastical law, prohibiting any new laws from being added, but, in fact, no new official collections of church law had been promulgated between the Clementinae and the Council of Trent (1545–63).

The bishops at the Council of Trent had requested new critical editions of Sacred Scripture, of liturgical books, and of the Corpus Juris Canonici.

In response to this request, a commission of cardinals and canonists have prepared a scientific critical edition of the Corpus between 1560 and 1582.

In 1582, Gregory XIII issues the revised text of the Corpus and ordered its use in schools of canon law and in church courts.

The Alexandrian astronomer Sosigenes, in creating the Julian calendar as a reform of the Roman republican calendar, had overestimated the length of the year by eleven minutes fourteen seconds, and by the mid-1500s, the cumulative effect of this error had shifted the dates of the seasons by about 10 days from Caesar's time.

Pope Gregory's reform, proclaimed in 1582, restores the calendar to the seasonal dates of CE 325, an adjustment of ten days.

Gregory bases his reform on restoration of the vernal equinox, now falling on March 11, to the date (March 21) it had in CE 325, the time of the Council of Nicaea, and not on the date of the equinox at the time of the birth of Christ, when it fell on March 25.

The change is effected by advancing the calendar ten days after October 4, 1582, the day following being reckoned as October 15.

The Gregorian calendar does not, however, include a year 0 in the transition from BC (years before Christ) to AD (those since his birth): the Gregorian calendar differs from the Julian only in that no century year is a leap year unless it is exactly divisible by 400 (e.g., 1600, 2000).

From this time forward, the Julian calendar will gradually be abandoned in favor of the Gregorian.

Ivan at last asks Pope Gregory XIII to intervene in the Livonian War, and through the mediation of his nuncio, Antonio Possevino, an armistice with Poland-Lithuania is concluded on January 15, 1582, ending a quarter-century of warfare over Russian access to the Baltic, which it has been unable to gain.

Under its terms Russia loses all its gains in Livonia.