By 1227 Frederick II was primed to lead his crusade: endowed with unprecedented military and political authority, buttressed by a promising Ayyubid pact. His German and Sicilian crusading forces duly assembled at the port of Brindisi that August in preparation for departure to the Holy Land, but then disaster struck. Amid the summer heat a virulent illness (perhaps cholera) began to spread through the army. Faced with the threat of excommunication, the emperor knew he could not afford to delay and so the embarkation began on schedule. Frederick himself set sail on 8 September in the company of the leading German noble Ludwig IV of Thuringia, but within days they too became sick. Fearing for his health, the emperor turned back, making landfall at Otranto (south of Brindisi). There can be little doubt that the panic was real and the delay necessary–Ludwig died from the illness at sea. Frederick declared that he would restart his journey in May 1228 after convalescing in southern Italy, and sent the Teutonic Master Herman of Salza on to the Near East to watch over the crusader host. Conscious of how events might be interpreted in Rome, the emperor also dispatched a messenger to the pope.²³

Honorius III had died in March that year, and his successor Pope Gregory IX was a hard-line reformer and a defender of papal prerogatives with little or no sympathy for the Hohenstaufen cause. Already suspicious of Frederick’s motives, Gregory greeted the news with stern action rather than understanding. Seizing the opportunity to curb what he regarded as the excessive power of the empire, he immediately enacted the terms of the San Germano treaty and excommunicated Frederick on 29 September. This was a severe act of censure, particularly given the emperor’s supposed status as a divinely ordained monarch; in theory, at least, it severed Frederick from the body of the Christian community, leaving him to be shunned by the faithful. The pope probably expected Frederick to seek reconciliation and absolution–to submit to Rome and make what would be a tacit admission of papal supremacy.

In fact, Frederick did nothing of the sort. Refusing to recognise his excommunication, he sent Riccardo Filangeri, one of his leading military officials, on to Palestine with 500 knights in April 1228. On 28 June the emperor followed, setting sail from Brindisi with a fleet of around seventy ships. He was taking a massive risk, leaving Sicily, in particular, exposed to the predations of an ambitious and unscrupulous pope–but Frederick now seems to have been determined finally to fulfil his crusading vow. He would arrive in the Holy Land as the most powerful leader ever to bear the sign of the cross, but also as an outcast, cut from the bosom of the Church.

Frederick II in the Near East

Over the preceding months, events had conspired further to diminish Frederick II’s chances for success in the Levant. Two deaths reshaped his prospects. In late 1227 al-Mu‘azzam died from a bout of dysentery, effectively nullifying the emperor’s projected alliance with al-Kamil. Then, in May 1228, Frederick’s young wife, Queen Isabella II of Jerusalem, passed away after giving birth to a son. This infant, Conrad, became the heir both to the Hohenstaufen Empire and–through his mother’s bloodline–to the kingdom of Jerusalem. In legal terms, this development weakened Frederick’s authority in Palestine. No longer would he be acting as the husband of a living queen, but rather as regent to the new child heir.

These significant setbacks hardly caused the emperor to break stride. He arrived on Cyprus on 21 July 1228 and proceeded to reaffirm Hohenstaufen overlordship of the island–a right first established by his father at the end of the twelfth century. Frederick removed Jean of Ibelin (who had been acting as regent for the young King Henry I) from power, accusing him of financial corruption, and secured imperial rights to the royal revenues of Cyprus before sailing on to Tyre and then south to Acre in early September.

Once on the mainland, Frederick’s excommunicate status caused only a limited degree of difficulty. The Latin Patriarch Gerold was distinctly uncooperative, and the Templars and Hospitallers were also slow to support the emperor’s campaign, but this was probably the result of resentment over open Hohenstaufen favouritism towards the Teutonic Order. More troubling was the diminution in martial resources suffered that autumn. Having spent the summer helping the Teutonic Knights with the construction of their new castle of Montfort in the hills east of Acre, a fair proportion of the crusade army had sailed back to Europe. Without recourse to overwhelming military strength, Frederick turned instead to negotiation, reopening channels of communication with al-Kamil and direct dialogue with his representative Fakhr al-Din.

Given al-Mu‘azzam’s death and the resultant shift in the balance of power in the Ayyubid world, al-Kamil was reluctant to honour his promises to the emperor and thereby risk provoking criticism within Islam for having needlessly made concessions to the Franks. At the same time, however, the sultan’s overriding priority was to secure full control over Damascus and not to become embroiled in a costly war with Frederick. To drive home the incipient threat of conflict, the emperor marched his remaining forces south from Acre to Jaffa in early 1229–mirroring Richard the Lionheart’s manoeuvre in 1191. The pressure began to tell, and as talks continued Frederick employed every artifice and argument to secure a favourable settlement and the return of the Holy City. At one point he extended the hand of cultured friendship by discussing questions of science and philosophy, but then shifted to threaten war; he argued that, to the Muslims, Jerusalem really was only a desolate ruin, but that its sanctity to the Christians was overwhelming. Worn down by these arguments, and with his eyes on Syria rather than Palestine, al-Kamil eventually conceded.

On 18 February 1229, Frederick agreed terms with the Ayyubid sultan. In return for a ten-year truce and Frederick’s military protection against all enemies, even Christians, al-Kamil surrendered Jerusalem, Bethlehem and Nazareth, together with a corridor of land linking the Holy City with the coast. Muslims were to retain access to the Haram as-Sharif, with their own qadi to supervise this sacred area, but otherwise they were to abandon the city. For the first time in forty years the Holy Sepulchre would again be in Christian hands–an excommunicate emperor had achieved what no crusader since 1187 could, and all without spilling a single drop of blood.

At first glance, this impressive accomplishment might appear to be an extraordinary break with tradition–an act that overturned the established principles of crusading: the embracing of peace; the rejection of the sword. This certainly is how Frederick’s recovery of Jerusalem has been presented by some modern historians–as proof that the emperor was gifted with a vision and sensibility beyond his times. Such a view relies upon simplification and distortion. While it is true that Frederick was the first crusade leader to secure such valuable gains through diplomacy, negotiation had played a prominent role in earlier campaigns. Indeed, the Hohenstaufen’s methods and objectives bear close comparison to those employed by Richard the Lionheart during the Third Crusade. It is also worth noting that, like Richard, Frederick needed to gird his talk of truce with martial intimidation. He seems to have turned to diplomacy, not from some heartfelt desire to avoid bloodshed, but rather because it was the most expedient means available to achieve his goal.

Once the deal was struck in 1229, events proceeded apace. One Muslim chronicler described how ‘after the truce the sultan sent out a proclamation that the Muslims were to leave Jerusalem and hand it over to the Franks. The Muslims left amid cries and groans and lamentations.’ Frederick entered Jerusalem on 17 March 1229, visiting the Dome of the Rock and the Aqsa mosque in the company of a Muslim guide. In the Church of the Holy Sepulchre he proudly placed the imperial crown on his head with his own hands in a ceremonial affirmation of his unrivalled majesty. To publicise and glorify his achievement, that same day the emperor wrote a letter to King Henry III of England from Jerusalem. In this missive Frederick likened himself to the Old Testament King David and declared that ‘[God] exalted us on high among the princes of the world’. After this fleeting visit, the emperor returned to Acre.²⁴