Frederick II, Holy Roman Emperor

• 1. Introduction

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  Frederick II was born in Jesi, near Ancona, on the 26th of December 1194, and the circumstances surrounding that birth were so extraordinary that rumors would follow him for the rest of his life. His mother, Queen Constance of Sicily, was considered too old to bear children, and the gossip spread quickly: according to chroniclers Albert of Stade and Salimbene, the infant presented to Emperor Henry VI was not his at all. His real father was described, depending on who was telling the story, as a butcher, a physician, a miller, or a falconer. Constance reportedly gave birth in the public square of Jesi to silence the doubters, and she swore on the gospels before a papal legate that Frederick was her son.

  The whispers never fully stopped. And in a way, that uneasy relationship between Frederick and official authority would define his entire life. By the time he died on the 13th of December 1250, he had been excommunicated four times, called the forerunner of the Antichrist by Pope Innocent IV, and hailed by others as the greatest ruler of the Middle Ages. He wore titles like a king of collections: King of Sicily from 1198, King of Germany from 1212, King of Italy and Holy Roman Emperor from 1220, King of Jerusalem from 1225 to 1228.

  He spoke six languages. He wrote poetry, studied mathematics, and corresponded with Islamic scholars. He built a centralized state in Sicily that would serve as a model of European governance for generations. He led a crusade while excommunicated and came back with Jerusalem through diplomacy, not warfare, only to be vilified for it.

  The questions worth asking about Frederick II are not simple ones. How did an orphaned, impoverished child in Palermo become the most powerful man in Europe? What kind of ruler rewrites the law, designs fortresses with mathematical precision, and exchanges philosophical puzzles with a sultan? And how does a man who came so close to reshaping the entire political map of medieval Europe leave behind a dynasty that collapsed almost immediately after his death?

• 2. A Turbulent Childhood

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  Frederick's tutor during his early years was Cardinal Cencio Savelli, who would go on to become Pope Honorius III. That detail captures something essential about the strange position the young Frederick occupied. He was simultaneously a ward of the papacy and a potential threat to it.

  His father, Henry VI, died on the 28th of September 1197, when Frederick was barely three years old. His mother Constance had him crowned King of Sicily on the 17th of May 1198, at just three years of age, and then she too died later that same year. Pope Innocent III succeeded as Frederick's guardian. The child king passed through the hands of self-serving regents: Markward of Annweiler, who invaded Sicily and seized the young Frederick with the help of Genoese ships in 1200; then William of Capparone, who kept Frederick under his control in the royal palace of Palermo until 1206; then his tutor Walter of Palearia, who supervised him until he was declared of age in 1208.

  During these years the Sicilian nobility grabbed much of the royal lands and wealth. Some chroniclers report that the young king was so destitute he had to seek shelter among the citizens of Palermo. Yet Frederick also roamed the cosmopolitan streets of the city, talking and arguing with all manner of people. By the time he was declared of age, he already spoke five languages: Greek, Arabic, Latin, Provençal, and Sicilian.

  His marriage was arranged by Pope Innocent: Constance of Aragon, a widow of Emeric, King of Hungary, and double Frederick's age. The match was a diplomatic calculation, not a romance. But Frederick's childhood, for all its instability, produced something unexpected. He emerged from those years with a personality described by those who knew him as precocious, insatiably curious, impatient of restraint, and already convinced of his own extraordinary destiny. The boy who had grown up with no stable home and no reliable protectors would spend the rest of his life building structures, legal and physical, designed to ensure that power would never slip away from him again.

• 3. Winning the Imperial Crown

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  Otto IV was crowned Holy Roman Emperor by Pope Innocent III in October 1209, and he almost immediately made an enemy of that same pope by invading Italy and pushing south toward Frederick's territory in Calabria. In September 1211, at the Diet of Nuremberg, Frederick was elected German King in absentia by a rebellious faction backed by Innocent. He sailed to Gaeta with a small following, then made a dangerous crossing through Lombardy and the Engadin, reaching Konstanz in September 1212 just a few hours ahead of Otto's forces.

  He was crowned King of Germany on the 9th of December 1212 in Mainz. His hold on the north remained fragile until the Battle of Bouvines, where Otto suffered a decisive military defeat. The German princes, backed by Innocent III, elected Frederick king again in 1215, and he was crowned in Aachen in mid-July of that year by one of the three German archbishops. The Aachen coronation was reinforced by deliberate symbolism linking Frederick to Charlemagne, and he made an unexpected announcement there: he would take the cross and go on crusade.

  In the following years, Frederick built his authority through a combination of reward and force. He recaptured key cities, including Aachen and Cologne, often without resistance. In 1218, he helped King Philip II of France and Odo III, Duke of Burgundy, end the War of Succession in Champagne by invading Lorraine, burning Nancy, and capturing Theobald I, Duke of Lorraine. At Eger in 1213, he had reaffirmed extensive concessions to Innocent III; later he issued the Confoederatio cum principibus ecclesiasticis, confirming the privileges of German ecclesiastical princes in exchange for dynastic support.

  After careful negotiations with the German princes in 1220, Frederick secured the election of his eldest son Henry as King of the Romans. By a precise legal maneuver, he retained his grip on southern Italy as regent for his son while keeping Henry in Germany as junior king, outflanking a papacy terrified of being squeezed between imperial Italy and the Sicilian kingdom. When Frederick finally received his imperial coronation in Rome on the 20th of November 1220, the papacy found itself facing the very encirclement it had feared.

• 4. The Sicilian State

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  By late 1220, Frederick crossed into southern Italy determined to reclaim what had been lost during his decades of minority. Under his grandfather Roger II and his successors William I and William II, the Norman Kingdom of Sicily had been arguably the most centralized state in all of Europe. The years of regency had dismantled much of that. Royal authority barely extended beyond Palermo.

  Frederick's first move was legislative. He issued the Assizes of Capua in December 1220, building on the earlier Assizes of Ariano of Roger II, and the legislation had been prepared before his return, down to the last detail. The Assizes demanded that all royal lands and castles be restored to the condition they were in at the death of William II, the last legitimate Norman king. All privileges granted since then had to be submitted to the Royal Chancery for confirmation before Easter 1221 for the mainland and before Whitsun for Sicily. Forged documents and spurious legal means used to grab royal land were comprehensively voided.

  Frederick then moved against the barons who refused to comply. He wrote to one of his captains: "Pretend some business and warily call the Castellan to you. Seize on him if you can and keep him till he cause the castle to be surrendered to you." Barons who resisted were besieged. When captured, they were exiled or executed, and their families sold into slavery. Over 1221-1222, he subdued most mainland resistance. The fortresses of Roccamandolfi and Ovindoli, held by Thomas of Celano, Count of Molise, surrendered after a long campaign. The town of Celano itself was razed and its inhabitants deported to Sicily.

  Frederick replaced the old feudal patchwork with a grid of mathematically precise fortresses, garrisoned by state troops at the expense of the local nobility. The Genoese and Pisan traders who had dominated Sicilian commerce were ejected, their warehouses confiscated. By the end of 1221 Frederick already had two squadrons at sea.

  The Muslim population of Sicily presented a different challenge. Between 1221 and the 1230s, Frederick deported them to the mainland, emptying the town of Lucera of its Christian inhabitants and replacing them with the relocated Sicilians, who were granted complete religious autonomy in exchange for a special tax. Six hundred served as his personal bodyguards; several thousand formed a standing army. The result was a loyal military force that could be deployed against Christian enemies or papal hostility without scruple.

  In 1231, the Constitutions of Melfi replaced this patchwork of earlier reforms with a comprehensive legal code. The code replaced clerical officialdom with lay jurists trained in Roman law and established a hierarchy reaching from the emperor down to the most subordinate provincial functionary. Frederick conceived of himself as the living law upon earth, deriving authority directly from God. That same year he issued the augustalis, a gold coin bearing his own image in the manner of the ancient Roman emperors rather than a Christian symbol. Dante would later identify Frederick's court in Palermo and Foggia as the birthplace of Italian vernacular poetry, with figures including the mathematician Leonardo Fibonacci, the poet Giacomo da Lentini, and the philosopher Theodore of Antioch gathered there.

• 5. Jerusalem Without a Crusade

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  Frederick had promised to go on crusade as far back as his election as King of the Romans. He delayed, repeatedly. He sent forces to Egypt under the command of Louis I, Duke of Bavaria, for the Fifth Crusade, but constant expectation of his own arrival caused the papal legate Pelagius to reject a peace offer from the Ayyubid sultan Al-Kamil, who had offered to restore the Latin Kingdom of Jerusalem in exchange for the crusaders' withdrawal from Egypt. The crusade ended in failure with the loss of Damietta in 1221, and Frederick was blamed.

  In 1225, Frederick married Isabella II of Jerusalem by proxy, which made him a claimant to the Kingdom of Jerusalem. He immediately moved to dispossess his new father-in-law, John of Brienne, and transfer John's rights to the emperor himself. When Frederick finally set out from Brindisi in August 1227, an epidemic struck his fleet, killing his friend Louis IV, Landgrave of Thuringia. Even Hermann of Salza, master of the Teutonic Knights, recommended Frederick return to recover. He did. On the 29th of September 1227, Pope Gregory IX excommunicated him anyway.

  Frederick sailed again from Brindisi in June 1228, and Gregory excommunicated him a second time. The crusading army was small, the local nobles distrustful, and the Templars and Hospitallers openly reluctant. So Frederick did something no Latin monarch had done before: he negotiated directly with the sultan. He and Al-Kamil exchanged philosophical and mathematical questions, poetry, and political reasoning. The treaty they signed on the 18th of February 1229 handed Jerusalem, Nazareth, Bethlehem, and a coastal strip to the Kingdom of Jerusalem for a period of ten years, while the Dome of the Rock and al-Aqsa Mosque remained under Muslim control and Jerusalem was to remain unfortified.

  Virtually every other crusader condemned it. The Templars, Hospitallers, and local Christian nobility called it a betrayal. When Frederick crowned himself King of Jerusalem on the 18th of March 1229, his wife Isabella had already died, leaving their infant son Conrad as rightful king. The Latin Patriarch of Jerusalem, Gerald of Lausanne, refused to attend; the Bishop of Caesarea placed the city under interdict the very next day.

  The coronation robe Frederick wore that day may have been the red silk mantle crafted during the reign of Roger II, bearing an Arabic inscription dated to the year 528 in the Muslim calendar, which corresponds to 1133-34. It carried a benediction wishing its wearer "vast prosperity, great generosity and high splendour, fame and magnificent endowments, and the fulfilment of his wishes and hopes. May his days and nights go in pleasure without end or change." That robe can be found today in the Schatzkammer of the Kunsthistorisches Museum in Vienna.

  Philip of Novara, a chronicler of the time, recorded Frederick's departure from Acre in a single sentence: "The emperor left Acre; hated, cursed, and vilified."

• 6. War Without End

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  While Frederick was in the Holy Land, his regent Rainald of Spoleto had attacked the March of Ancona and the Duchy of Spoleto. Gregory IX used this as justification for a military campaign against the Kingdom of Sicily, collecting church funds across Europe and recruiting Frederick's former father-in-law John of Brienne to lead the invasion. John's forces reached into Campania as far as the Volturno-Calore Irpino before Frederick's surprise return to Brindisi in June 1229 reversed the momentum. Frederick rallied loyal forces and drove the papal armies back. By late 1229, he had fully restored control.

  The two sides reached a settlement at the Treaty of San Germano in July 1230. On the 28th of August, in a public ceremony at Ceprano, the papal legates Thomas of Capua and Giovanni Colonna lifted Frederick's excommunication. He met Gregory personally at Anagni and made limited concessions on clerical privileges and property in Sicily. The peace lasted less than a decade.

  After his great victory over the Lombard League at the Battle of Cortenuova in November 1237, Frederick celebrated in Cremona with a triumph modeled on ancient Roman ceremony, parading the captured carroccio of the defeated communes alongside an elephant. At what appeared to be the peak of his power, he refused any conditional peace from his enemies, even rejecting an offer from Milan that came with a great sum of money. His demand for total subjection drove the holdout cities toward greater resistance.

  His second excommunication arrived in the first months of 1239. The emperor responded by expelling the Franciscans and Dominicans from Lombardy, annexing the Duchy of Spoleto and Romagna through his son Enzo, and purging the Sicilian church of Gregory's supporters. Berard of Castagna, Archbishop of Palermo, was appointed nominal head of a Sicilian church that had effectively severed itself from Rome.

  The war reached its strangest moment at the Battle of Giglio in 1241, when Frederick's forces intercepted a fleet carrying a delegation of prelates traveling to Rome for Gregory's General Council, capturing thousands of prisoners, including most of the high dignitaries of the church. Frederick proclaimed the victory divine judgment. He then marched on Rome. But on the 22nd of August 1241, before his troops could attack, Gregory died. Frederick withdrew, freed two captured cardinals from his prison at Capua, and waited.

  His manipulation of the subsequent papal election was direct and deliberate: imperial armies surrounded Rome, blocking hostile cardinal electors. The cardinals, locked in the Septasolium monastery by Roman civic officials, eventually settled on their oldest and most feeble member, Goffredo da Castiglione. Pope Celestine IV proved amenable to Frederick's interests but died shortly after election in November 1241. The cardinals dispersed for over a year before coming together in Anagni to elect a successor. Frederick had effectively created the first of the long papal vacancies that would come to define the later Middle Ages.

  A new pope, Innocent IV, was elected on the 25th of June 1243. Frederick was reportedly optimistic at first, given Innocent's Genoese family and Ghibelline connections. He would later exclaim bitterly: "No pope can be a Ghibelline." Innocent IV would call Frederick preambulus Antichristi, forerunner of the Antichrist, and the war between them continued until Frederick's death on the 13th of December 1250.

• 7. The Polymath Emperor

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  Frederick reportedly spoke six languages: Latin, Sicilian, Middle High German, Old French, Greek, and Arabic. He was the first monarch to formally outlaw trial by ordeal, which had come to be viewed as superstitious. He wrote poetry, studied natural philosophy, and maintained a court that blended Roman legal tradition, Arabic philosophical inquiry, and Byzantine administrative practice.

  His appellation Stupor mundi, meaning Wonder of the World, captured how contemporaries understood him: a figure who exceeded the normal categories. He surrounded himself with scholars regardless of their religion or origin, treating them as intellectual peers. Among his court's notable figures were Michael Scotus, described as a celebrated Scottish polymath; the astrologer Guido Bonatti; the mathematician Leonardo Fibonacci; the philosopher Theodore of Antioch; the poet Giacomo da Lentini, who is associated with the development of the sonnet form; and the jurist Piero della Vigna, who became Frederick's chief minister.

  Frederick's court in Palermo, beginning around 1220, hosted what would be called the Sicilian School of poetry. The literary form developed there had a decisive influence on what became the modern Italian language. Dante later identified Frederick's court as the birthplace of Italian vernacular poetry.

  His interest in the natural world was direct and personal. Even as a young king, he had been passionately interested in nature and the study of the universe. That curiosity never faded. He exchanged philosophical and mathematical questions with Al-Kamil, the Ayyubid sultan, during their negotiations in the Holy Land. The augustalis coin he issued in 1231 bore his own face in the style of the ancient Caesars, a deliberate statement about his conception of authority as rooted in the classical world rather than in Christian symbolism alone.

  For all the warfare and excommunications, the robe Frederick wore at his Jerusalem coronation, with its Arabic blessing stitched into the silk and its date in the Muslim calendar, tells a different story. It speaks of a ruler formed by Sicily's layered cultures: Norman, Arab, Byzantine, Latin. The robe survived him and still exists in Vienna, a fabric record of the world that shaped him.