Pope Gregory IX (1227-1241)

The Pope Who Codified Church Law

Before Gregory IX, Church law was scattered across a mosaic of partial collections—the quinque compilationes antiquae—often redundant and sometimes contradictory.^[10] By entrusting Raymond of Peñafort with the task of drafting a single, official, and exclusive compilation, and by imposing it on the universities of Bologna and Paris, Gregory IX ushered the West into the age of codified law. The Decretals of 1234 are to the legal history of the Church what the Napoleonic Code would be to French civil law: a foundational text, studied, commented on, and applied for nearly seven centuries.^[11]

The Pope of Saint Francis and the Mendicant Orders

The 13th century saw the emergence of a new form of religious life: no longer the monk cloistered in his abbey, but the mendicant friar who preached along the roads, lived on alms, and evangelized burgeoning cities. Gregory IX understood, better than anyone in the Curia, that these Franciscans and Dominicans were a grace for the Church. He protected them, structured them, entrusted them with teaching, preaching, and soon the Inquisition. Canonizing Francis, Dominic, and Anthony was a way to inscribe in stone that this spiritual revolution came from God.^[12]

The Pope of the Long Duel with the Empire

Finally, Gregory IX was the pope who confronted Frederick II, heir to the struggle that Gregory VII and then Alexander III had waged for libertas Ecclesiae. The issue was not a prideful quarrel between two stubborn old men: it was the question of whether the successor of Peter could govern Christendom freely, or whether he must bow before an emperor who dreamed of a Church subject to the State. Gregory IX held firm, until his last breath, that the pope does not bow before Caesar.^[13]

A Birth in Anagni, in the Shadow of Innocent III

Ugolino was born in Anagni, in Lazio, a city that would give several popes to the Church. His birth date is debated: tradition, echoed by the Catholic Encyclopedia, places it around 1145, which would make him nearly a hundred at his death; modern historical criticism leans toward circa 1170.^[14][15] The difference matters little for the essentials: Ugolino belonged to the powerful house of the Counts of Segni, the same family as Pope Innocent III, to whom he was either a nephew or close relative. This kinship immediately placed him at the heart of Church governance.

He was educated in the two great sciences of his time, in the two intellectual capitals of Christendom: theology in Paris, and law in Bologna.^[16] From this dual education emerged a man: a mind both spiritual and legal, capable of loving a saint like Francis and of building a code like the Decretals.

Cardinal-Deacon, Then Cardinal-Bishop of Ostia

In December 1198, his uncle Innocent III made him cardinal-deacon of Sant'Eustachio.^[17] In 1206, he became cardinal-bishop of Ostia and Velletri—one of the most prestigious suburbicarian sees, traditionally reserved for the highest dignitary of the Sacred College. Around 1218-1219, under Honorius III, Ugolino rose to the deanery of the Sacred College: he was now the first among the cardinals.^[18]

For three decades, he served the Church in the highest diplomatic roles. Innocent III and then Honorius III sent him as legate to Lombardy and Tuscany, regions troubled by the Cathar heresy and torn by city conflicts. There, Ugolino learned the art of governance, negotiation, firmness—and direct contact with new spiritual movements.

The Protector of the New Orders

It was as cardinal that Ugolino forged the decisive bond of his life: he became the cardinal protector of the Franciscans. The Catholic Encyclopedia reports a revealing detail: when he was cardinal-bishop of Ostia, Ugolino “often wore the habit of Saint Francis.”^[19] Far from being a distant prelate, he loved these poor brothers so much that he shared their sign.

“This man was a light, despised by the rich yet prepared for the appointed time. [...] The Lord sent him into his vineyard to uproot thorns and brambles.” — Gregory IX, bull Mira circa nos, about Francis of Assisi, Perugia, 1228^[20]

This bond made Ugolino the bridge between the Church hierarchy and the spiritual spring of the 13th century. When he became pope, he only elevated to pontifical policy what he had already practiced as cardinal: trust in the mendicants.

The Death of Honorius III

Honorius III died on March 18, 1227. The very next day, March 19, 1227, the cardinals gathered and elected Ugolino, who took the name Gregory IX—likely in homage to Gregory VII, the great pope and reformer of the Church’s freedom.^[21] The election was swift and uncontested: the dean of the Sacred College, experienced and respected, naturally prevailed.

An Elderly Man at the Head of Christendom

Gregory IX ascended to the papacy already very old—an octogenarian according to traditional chronology. One might have expected a brief, transitional, and cautious reign. Instead, it was quite the opposite: fourteen years of overflowing activity and energy admired even by his adversaries. Gregory IX’s old age disproves the stereotype of a “pope at the end of his career”: his pontificate was one of the most creative of the Middle Ages.

A Program: Crusade, Reform, Defense of the Faith

Three major projects shaped his reign from the very first months: reviving the crusade promised for the Holy Land, reforming the Church through law and new orders, and defending the faith against heresy. Each of these goals would, in its own way, plunge him into conflict with Frederick II, into the codification of canon law, and into the foundation of the Inquisition.

The Cardinal Protector and Friend

The friendship between Ugolino and Francis is one of the most beautiful chapters in the spiritual history of the Middle Ages. The cardinal supported Francis in moments of doubt, defended the ideal of radical poverty while giving it a viable form within the Church, and watched over the young community as it grew too quickly for its founder.^[22][23] Francis, for his part, saw in Ugolino a faithful protector and himself appointed him as guardian of the Order.

The Rule of 1223 and Ugolino’s Role

When the Franciscan Order needed an approved Rule, it was again Ugolino who helped formulate the definitive text—the Regula bullata—confirmed by Honorius III in 1223. The cardinal played the delicate role of mediator between Francis’s uncompromising stance on absolute poverty and the practical demands of an order that had become international.^[24] This was Ugolino’s art: preserving the spirit by giving it a lasting form.

The Canonization of Francis: Mira circa nos (1228)

Francis died on October 3, 1226. Less than two years later, on July 16, 1228, Gregory IX solemnly canonized him at Assisi and laid the first stone of the basilica that would house him the very next day.^[25][26] The canonization bull, Mira circa nos (“The wonders God has worked among us”), dated from Perugia, fixed his feast day on October 4.^[27]

“He no longer lived for himself, but for Christ, who died for our sins.” — Gregory IX, bull Mira circa nos, on Saint Francis of Assisi, 1228^[28]

To canonize so quickly the man of the stigmata—the first officially recognized stigmatized in Church history—was a bold and confident act of discernment. Gregory IX, who had known Francis in life, knew what he was doing: he sealed with the Church’s stamp the holiness of a man he had loved.^[29]

Clare of Assisi and the Poor Ladies

Gregory IX extended this protection to Clare of Assisi and her Poor Ladies—the future Poor Clares. He wrote a rule for them and maintained a spiritual correspondence marked by genuine paternal tenderness. Again, he defended their ideal of poverty while seeking to make it canonically sustainable over time.

A Harvest of Saints

Gregory IX’s pontificate was one of the most fruitful in canonizations in all medieval history. In just a few years, he raised to the altars the great figures of spiritual renewal:

The Unkept Crusade Oath

Frederick II of Hohenstaufen, King of Sicily, King of Germany, and Emperor, had made the solemn vow to go on crusade. Year after year, he delays. For Gregory IX, this is not a mere diplomatic detail: a Christian emperor who breaks his crusader oath endangers the salvation of the Holy Land and defies the spiritual authority that received this vow.^[31]

The First Excommunication (September 29, 1227)

In September 1227, Frederick finally sets sail from Brindisi but turns back after three days, citing an epidemic devastating his army. Gregory IX, refusing this excuse, excommunicates the emperor on September 29, 1227; he solemnly renews the sentence on Maundy Thursday of 1228.^[32][33] The reason is clear: no one, not even an emperor, is above the word given to God and the Church.

The Crusade of the Excommunicated (1228–1229)

Then occurs a unique episode in history: Frederick II goes on crusade while excommunicated. In 1228–1229, more by negotiation than by arms, he obtains from the Sultan of Egypt the restitution of Jerusalem and is crowned king there.^[34][35] The paradox is complete: the emperor under anathema reconquers the Holy City that Christendom mourned. Gregory IX sees this as a provocation—a crusade carried out against the will of the Church, for the glory of a single man. During Frederick’s absence, papal troops enter the Kingdom of Sicily: this is the “War of the Keys.”

The Peace of San Germano (1230)

Back in Italy, Frederick repels papal armies but seeks an agreement. The Peace of San Germano, concluded on July 23, 1230^[36], ends the conflict; the excommunication is lifted at Ceprano on August 28, 1230, and the emperor even dines with the pope at Anagni as a sign of reconciliation.^[37] A decade of fragile armed peace follows, during which each side consolidates its forces. During these years, Gregory IX can devote himself to his legislative and spiritual work.

The Second Excommunication (March 20, 1239)

The truce breaks over Italy. Frederick wants to subdue the Lombard cities and make the peninsula an imperial bloc encircling the Papal States. For Gregory IX, it is the very freedom of the Holy See that is threatened. On March 20, 1239, Palm Sunday, he excommunicates the emperor again.^[38][39] This time, the break is final: it will be war until death.

The War of Words: the Beast and the Dragon

The conflict spills beyond arms to become a propaganda war of unprecedented violence, the first of such scale in European history. In his 1239 encyclical, Gregory IX designates Frederick as the Beast rising from the sea of the Apocalypse, “full of blasphemous names.”^[40]

In this encyclical, the pope applies to the emperor the images of the Apocalypse (chap. 13): the beast rising from the sea, marked with blasphemous names^[41].

The emperor replies with equal vehemence: he compares the pope to the rider on the red horse who takes peace from the earth, calls him a wild beast, an antichrist, a “second Balaam” who sells blessings and curses.^[42] This apocalyptic escalation, more passionate than reasoned, reveals the stakes as experienced by contemporaries: they were not disputing a province, but believed the fate of Christendom was at stake.

The Prevented Council and the Disaster at Giglio (1241)

To have the emperor judged by the universal Church, Gregory IX convenes a council in Rome for Easter 1241. Frederick II decides to prevent it by force. On May 3, 1241, off the island of Giglio (north of Tuscany), the Pisan fleet allied with the emperor crushes the Genoese fleet transporting prelates to Rome: many cardinals, archbishops, and bishops are captured and imprisoned.^[43][44] The blow is severe: the council cannot be held.

Gregory IX dies on August 22, 1241, in Rome, while Frederick’s armies camp at the gates of the City.^[45] The duel is unresolved: it will take Innocent IV and the First Council of Lyon (1245) for the Church to solemnly depose the emperor. But it is Gregory IX who held the line, to the very end, without yielding. Here is a summary of the great confrontation presented as a timeline:

Why a New Code of Law?

At the beginning of the 13th century, Church law was a thicket. To the Decretum Gratiani (circa 1140) had been added five private collections of decretals—the quinque compilationes antiquae—which overlapped, sometimes contradicted each other, and which no authority had unified.^[46] Finding the applicable norm required scholarship that few jurists possessed. Gregory IX himself, in the preamble to the promulgating bull, invoked “the inconvenience of having to resort to several collections containing very diverse and sometimes contradictory decisions.”^[47]

Raymond of Peñafort, the Craftsman

To carry out the project, Gregory IX chose his chaplain and confessor, the Catalan Dominican Raymond of Peñafort, one of the greatest canonists of his time. In about four years, Raymond gathered, pruned, and harmonized some 1,970 chapters, eliminating repetitions, resolving contradictions, modifying the text of old decretals when necessary to make them coherent—a task not of a mere compiler but of a true legislative editor.^[48] Most texts came from earlier compilations; one hundred ninety-one were new decretals issued by Gregory IX himself.

Rex pacificus: The Promulgation (5 September 1234)

On 5 September 1234, by the bull Rex pacificus, Gregory IX promulgated the work and sent it to the universities of Bologna and Paris, the centers of legal education. The act’s significance was decisive: the pope declared that this compilation alone has authority, forbade anyone to compose another without express papal permission, and deprived of legal force any decretal not included.^[49][50] Thus, the Church moved from customary law accumulated over time to promulgated positive law.

“Let all use this single compilation in judgments and in schools.” — Principle of the bull Rex pacificus, Gregory IX, 5 September 1234^[51]

Five Books: Judge, Judgment, Clergy, Marriage, Crime

The work, called Liber Extra (the “book [of decretals gathered] outside” the Decretum Gratiani), is organized into five books, which medieval jurists memorized by a mnemonic verse: iudex, iudicium, clerus, connubia, crimen — the judge (organization and hierarchy), the judgment (procedure), the clergy (life and discipline of clerics), marriage (matrimonial law), and crime (criminal law and heresy).^[52] This clear structure, inherited from Bernard of Pavia, became the reference framework for all canon law scholarship.

An Authority Lasting Until 1917

The Decretals of Gregory IX became central to the Corpus Juris Canonici, alongside the Decretum Gratiani, Boniface VIII’s Liber Sextus (1298), the Clementines (1317), and the Extravagantes. This collection, approved as authentic by Gregory XIII in 1582, remained the living law of the Church for nearly seven centuries, until the promulgation of the first Code of Canon Law in 1917.^[53][54] Few popes can claim such a lasting legacy.

From Episcopal Inquiry to Papal Inquiry

The fight against Cathar heresy, organized since the Third Lateran Council (1179) and the decretal Ad abolendam of Pope Lucius III (1184), had until then relied on the bishops.^[55] The Fourth Lateran Council (1215) had toughened the arsenal. But diocesan investigations proved uneven, sometimes lax, sometimes brutal. Gregory IX decided to professionalize the repression of heresy by entrusting it to judges delegated directly by the pope.

Excommunicamus, Ille humani generis, and the Dominicans

The constitution Excommunicamus (February 1231) reprises and systematizes the anti-heresy arsenal.^[56] Above all, through a series of bulls in April 1233 — including Ille humani generis (April 20, 1233), addressed to the Dominican priors of Toulouse and Albi — Gregory IX delegates papal investigative powers to the Dominican order.^[57] The Papal Inquisition is born: not as a brutal novelty, but as the regularization of a procedure that had until then been scattered. The details of its functioning, its safeguards, and the dark legend surrounding it are treated in the article dedicated to heretics and the dark legend of the Inquisition.

Conrad of Marburg: Early Excesses and Their Correction

The institution experienced serious abuses from its inception. Conrad of Marburg, appointed by Gregory IX as inquisitor for the Holy Roman Empire in 1231, conducted a summary procedure and quickly executed several German nobles. The protest of the Rhenish bishops led Rome to moderate his powers; Conrad was assassinated on July 30, 1233.^[58] This case reveals a frequently overlooked trait: from the start, the papacy monitored its own inquisitors and could disavow them. The foundation of the Inquisition by Gregory IX was not a descent into fanaticism, but an — imperfect — attempt to legally frame a repression that, when left to mobs or princes, had been far more blind.

The 1229 Strike and the Pope’s Arbitration

In 1229, a violent conflict opposed the masters and students of Paris to the bishop and the kingdom’s regent. The university corporation went on strike; classes stopped for two years, and some masters dispersed to Reims, Toulouse, and Oxford.^[59] Gregory IX, himself a former student of Paris, intervened as arbiter and sealed the restoration by the bull Parens Scientiarum, promulgated on April 13, 1231.

The “Mother of the Sciences”

The name of the bull is a program: Parens Scientiarum, “the mother of the sciences.” The text guarantees the university the freedom to establish its own statutes, regulates the power of the chancellor, and consecrates the autonomy of the scholarly corporation.^[60]

In its preamble, the bull celebrates Paris, mother of the sciences, as a new Cariath-Sepher: a city of letters whose radiance promises still greater fruits, dear to its masters as to its students.^[61]

By thus protecting the University of Paris, Gregory IX fostered the rise of scholasticism: it is in this framework, and thanks to this freedom guaranteed by Rome, that Albert the Great, Thomas Aquinas, and Bonaventure would soon teach. Far from the image of a Church hostile to knowledge, the pope here acts as the institutional guarantor of the intellectual life of Christendom.^[62]

An Inquiry into the Talmud (1239)

The pontificate of Gregory IX also marks a delicate chapter: the examination of the Talmud. In 1239, alerted notably by the convert Nicholas Donin, Gregory IX sent letters to the kings and prelates of Christendom ordering the seizure and examination of Talmudic books, suspected of containing blasphemies against Christ and the Christian faith.^[63] The matter would lead, after Gregory’s death, to the famous Disputation of Paris (1240) and the burning of Talmudic manuscripts in 1242, under the reign of Saint Louis.

It is important here, in historical honesty, to distinguish levels. Gregory IX’s action targeted texts deemed offensive, not the existence of Judaism as such: the consistent doctrine of the Church, recalled by Innocent III in the bull Sicut Judaeis, protected Jewish persons against violence and forced conversions. Nonetheless, the Talmud episode remains a moment of tension that serious Catholic historiography neither seeks to conceal nor exaggerate, but to understand in its context, without projecting today’s categories onto the 13th century.

August 22, 1241

Gregory IX died on August 22, 1241, in Rome, after a reign of more than fourteen years, while Frederick II’s army was camped outside the city walls.^[64] According to traditional chronology, he died almost a centenarian. His successor, Celestine IV, elected in a besieged Rome, reigned only seventeen days; it would take nearly two years to elect Innocent IV, who would resume the struggle.

A Vast Legacy

Few medieval pontificates leave such a profound mark. Gregory IX bequeathed to the Church:

• a code of law — the Decretals — which governed it until 1917;
• an institution — the papal Inquisition — for better and worse in its later applications;
• a constellation of saints — Francis, Anthony, Dominic, Elizabeth — who remain among the most beloved in Christendom;
• the charter of the greatest university of the Middle Ages;
• and the example of a pope who, in old age, never yielded on the freedom of the Church before the most powerful prince of his time.

What This Pontificate Reveals

The Freedom of the Church before Temporal Power

The duel with Frederick II was not a quarrel of ambitions. It posed the decisive question: can the successor of Peter govern freely, or must he become a chaplain of the Empire? By holding firm until his death, Gregory IX passed on intact to his successors the conviction that spiritual authority answers to no throne. This was the same cause defended by Gregory VII and Alexander III, now under new conditions.

Law in the Service of Communion

For the Church, codifying law is not a bureaucratic gesture. Clear law protects the weak against arbitrariness, guarantees procedures, and orders communal life. Gregory IX’s Decretals gave Christendom a common legal language, from Lisbon to Krakow. The canonist pope understood that charity needs institutions to endure.

Recognized Holiness, Not Imposed

Finally, this pontificate reveals a Church confident in God’s action. By canonizing Francis and Dominic so swiftly, Gregory IX did not yield to a fad: he discerned, at the heart of a troubled century, the movement of the Spirit. The same pope who built legal codes knew how to kneel before a saint in rags. Perhaps this is the secret of his greatness: holding together law and holiness, the firmness of the ruler and the tenderness of Francis’s friend.

Primary Sources and Medieval Corpus

The acts of the pontificate are collected in the Registers of Gregory IX edited by Lucien Auvray (Bibliothèque des Écoles françaises d'Athènes et de Rome), a primary source for papal diplomacy. The major bulls — Mira circa nos (canonization of Francis), Rex pacificus (promulgation of the Decretals), Parens Scientiarum (University of Paris), Excommunicamus and Ille humani generis (Inquisition) — are cited according to their editions and canonical collections. The text of the Decretals appears in the reference edition by Emil Friedberg, Corpus Iuris Canonici, vol. II, Leipzig, 1879-1881.^[65][66]

Modern Scholarly Sources

On Frederick II and the conflict, the reference monograph is David Abulafia, Frederick II: A Medieval Emperor, Allen Lane, 1988.^[67] On canon law, see James A. Brundage, Medieval Canon Law, Longman, 1995, and the study of the edition of the Decretals by Raymond of Peñafort.^[68][69] On the Franciscans, John R. H. Moorman, A History of the Franciscan Order from its Origins to the Year 1517, Oxford, 1968, and Augustine Thompson, Francis of Assisi: A New Biography, Cornell University Press, 2012.^[70][71] The classic account of the propaganda war is found in Philip Schaff, History of the Christian Church, vol. V.^[72]

Encyclopedic and Reference Sources

Cross-referenced entries — Catholic Encyclopedia (1907), Encyclopædia Britannica, Wikipedia — provide the basic factual and chronological framework, to be systematically compared with primary sources and monographs.^[73][74]

• Pope Honorius III — the predecessor of Gregory IX, who approved the Franciscan Rule of 1223.
• Pope Innocent III — Ugolino’s uncle and the most powerful pope of the Middle Ages.
• Pope Innocent IV — the pope who, at the First Council of Lyon (1245), deposed Frederick II.
• First Council of Lyon (1245) — the culmination of the conflict with the Empire.
• Fourth Lateran Council (1215) — the great council of Innocent III whose work Gregory IX continued.
• Saint Francis of Assisi — the friend whom Gregory IX canonized in 1228.
• The Heretics and the Black Legend of the Inquisition — the institution organized by Gregory IX.
• The University of Paris and Scholasticism — the scholarly corporation granted its charter by Parens Scientiarum.
• The 1917 Code of Canon Law — the distant heir of Gregory IX’s Decretals.
• Pope Alexander III — another great canonist pope and defender of the Church’s freedom.