he Middle Ages were not only a time of religious fervour, intolerance, and violence but also a time when people were thirsty for knowledge and adventure, a time of economic and cultural exchange. The contact with Muslim countries was by no means always violent — Western Europe imported sugar, spices and valuable cloth. In return, it exported wood, fur, and silver from newly developed mines. Alexandria and other cities in Egypt had significant colonies of Italian merchants, and the Crusader States in Outremer (roughly today’s Israel, Palestine, Lebanon and the coastal parts of Syria) depended on trade. They were enmeshed in local alliances — Christians and Muslims fought each other, but also side by side.

With rising prosperity, Western Europe eagerly searched the knowledge of the East. Gebert of Aurillac (946–1003), who lived as a Monk in Barcelona and later became Pope (Sylvester II), introduced Arabic numbers to Western Europe — later, legends made him a magician. The Qur’an was translated into Latin around 1150 (this translation was used until the 18th century). Then in the 13th century, a significant knowledge transfer began — texts about Medicine, Botany, Astronomy, Agriculture, Animal husbandry and Philosophy were obtained from Constantinople and the Muslim world and translated. Some of these texts were from Latin and Greek authors, long lost in the West, now often only available in Arabic; others were the work of Muslim scholars. An intellectual revolution started at the newly founded Universities and Cathedral Schools when Aristotle was rediscovered, his works accompanied by the commentaries written by Ibn Sina (Avicenna) and Ibn Rushd (Averroes).

The Emperor

One of the knowledge transfer centres was the court established by Emperor Frederick II in Palermo. The Emperor was red-haired, stout, balding, and short-sighted. His intellect impressed people — he spoke six languages, Greek and Arabic among them, and was well versed in the science of his time. However, only his studies of birds show originality. Seeing himself as a theocratic ruler like an orthodox Emperor or a Muslim Sultan, he did not fit into the Western Medieval world (tellingly, his negotiations with Muslim rulers were more successful than with Christians).

In Sicily and southern Italy, he established absolute rule and founded a state that seems more modern than medieval to us. At his court, scholars and translators like Michael Scot (who did double duties as an Astrologer) and Theodore of Antioch worked, and the Mathematician Leonardo Fibonacci was a guest. Also at court were the Emperor’s Muslim bodyguards, his private Arabic grammar teacher, and his personal chamberlain Johannes Morus, a black man and ex-slave. The Emperor wrote a book about birds and falconry (“De Arte Venandi cum Avibus”), and he and other members wrote poetry in the local dialect.

Frederick II was born in 1194 in Central Italy. His father, the German Emperor Henry VI, died three years later, and his mother brought him to Palermo, the city where she had grown up. There he was crowned King of Sicily in 1198, with his mother acting as Regent. When she died soon afterwards, Pope Innocent III became his guardian, but in reality, he was at the mercy of local Barons and Bishops, often living in poverty. In 1208 he was declared of age and slowly started to rebuild his kingdom in Sicily and southern Italy.

Frederick’s fortune improved when the Pope had a falling out with the German Emperor Otto IV. After being crowned in Rome, Otto IV tried to extend his rule to southern Italy. An Emperor strong in Italy and Germany threatened the Pope’s dominion, who in turn supported rebels in Germany aligned with Frederick’s family, the Hohenstaufen family. Otto IV was excommunicated and allied with England. The defeat of the German — English (or better Plantagenet — Guelph) Alliance by the French at Bouvines (1214) left him without followers and Allies. Frederick was elected King of Germany in 1215. He seldom visited his kingdom, which was ruled in his name by his son Henry and later Conrad, with Bishops and Dukes acting as Regents during the princes’ minority.

The Fifth Crusade

After the Fourth Crusade went off track and ended in 1204 with the conquest of Christian Constantinople (a success for Venetian Diplomacy), Pope Innocent III started pushing for another Crusade and was finally successful. However, he did not live to see the arrival of the Crusaders in Outremer, where desultory campaigns began in 1217. Then, in 1218 a fleet from Northern Europe, manned by Frisians (people living in Northern Germany and the Netherlands), arrived, and the Crusaders attacked Damietta, a fortified city in the Nile Delta. This shift towards Egypt seems strange but was entirely rational given the situation at the time: An attack on Egypt was an attack on the core of the Muslim power in the area, and it also kept the often over-enthusiastic and undisciplined Crusaders away from the vital trade routes and the Syrian Muslims, which were more often than not allied with Outremer.

The siege of Damietta began in May 1218 and dragged on — the Crusaders, reinforced by English and French Nobles, finally took the city in November 1219. The Sultan offered Jerusalem and parts of Palestine for Damietta’s return, but the Barons of Outremer insisted that the fortresses of Oultrejourdain (the Negev and parts of Jordan) should be part of the package. These fortresses controlled the connection between Egypt and Syria, and the Barons reasoned (probably correctly) that without them, Jerusalem could not be held for a more extended period. The Sultan refused this condition.

While the negotiations dragged on, some Crusaders went home, and others stayed in Damietta, squabbling, waiting for Frederick II, who had taken the cross in 1215 but only sent troops. An attempt to take the offensive ended in disaster: the army got isolated on an island in the rising Nile and had to capitulate. The Crusaders had to give up Damietta and agree to an eight-year truce to regain their freedom.

Despite the missed Crusade, Frederick’s relationship with the Pope remained good, and in 1220 he was crowned Emperor in Rome. After his first wife died, he married Isabella, heiress, to Jerusalem’s crown in 1225. Now the Emperor was also Regent of Jerusalem (ruling in his wife’s name), a title with little power, but at least nominally, he was the Lord of the Barons in Outremer. The marriage, however, was not happy, and Frederick mistreated his wife (for example, it seems that he had a tryst with one of her cousins on the night of the wedding). Isabella was kept like a prisoner at the Emperor’s court and died in 1228, right after having born a boy.

The excommunicated Crusader

The marriage had increased Frederick’s obligation to go on a Crusade, but still, the Emperor dawdled, probably reluctant to leave his lands. This position was popular in Outremer, where the Barons hoped that the next Crusade would only arrive at their lands in 1229, after the expiry of the truce with Egypt. Then Pope Honorius III died, and the newly elected Gregor IX was much less friendly towards Frederick II than his predecessor. The Crusade, already planned for 1227, became a political necessity. Frederick gathered an army in Germany and Italy. The troops met in Brindisi in August; leaving then would allow the army to arrive in Outremer in early autumn and to conduct its campaign in the milder autumn- and winter climate. However, August was a terrible month to gather a lot of troops in southern Italy. Malaria spread and the bad sanitary conditions did their part — the first ships had already sailed when a good part of the army fell ill and died.

While some troops reached Outremer, Frederick fell ill and stayed in Italy to regain his health. The Crusade had failed, and Gregor IX had the opportunity to strike — for him, the Emperor was somebody who threatened the Church’s worldly possessions in Italy. Additionally, the Emperor’s right to select Bishops and Archbishops or at least to influence their selection, a right that the Emperor had for many seats, was seen as a threat to the Church’s spiritual independence and worldly influence. Theological considerations aside, as a Pope, you could sell a vacant Bishop’s seat or give it to one of your nephews, and you didn’t want the Emperor to upset this racket.

The Pope excommunicated the Emperor for not keeping his vow and added a twist to the Excommunication: He declared that the Emperor could not go on a Crusade while excommunicated and would stay excommunicated until he went on a Crusade. Frederick II then put his spin on the Crusade — he now went to Outremer with a relatively small army, not intent on military conquest but on achieving his gains through diplomacy. Negotiations were going well, and a draft for an agreement was already in place when he left Italy in the summer of 1228.

The ‘Conquest’ of Jerusalem

After an extended stopover in Cyprus, where he tried with little success to sort out local rivalries, Frederick II landed in Acre in September 1228. He had little support from the local Barons. As his wife had died, Frederick II was only acting as the Regent for their son Conrad, quite a weak position according to the laws of Outremer. The news of his Excommunication, arriving a few days after him, made the relations even more difficult. He could only depend on the knights from southern Italy and Germany and the Teutonic Order. Diplomacy was his only real option.

Unfortunately, diplomacy suddenly didn’t work too well either. The descendants of Saladin, the Ayyubids, ruled Egypt and Syria. After Saladin’s death, his brother al-Adil emerged as Sultan of Egypt after long struggles, pushing his nephews aside. His son, al-Kamil, succeeded him in 1218, driving the Crusaders out of Egypt and reconquering Damietta in 1221. Al-Kamil’s two brothers, sometimes Allies and sometimes rivals, ruled in Palestina, Syria, and Transjordan. In the background were the Seljuks ruling in Anatolia, the Khwarazmians stretching towards Baghdad, and behind them, the Mongols, threatening Invasion. Al-Kamil’s main rival was his brother al-Mu’azzim, ruling in Damaskus, and the Alliance with Frederick had aimed at him, but al-Mu’azzim had died late in 1227, and his young heir was soon besieged in Damascus.

Now Frederick II was an unwelcome guest even in the eyes of Sultan al-Kamil — he was with his army before the walls of Damascus and now had to worry about the Emperor in Acre and his army, not big enough to be dangerous in battle but a sufficient threat for an army in a siege camp. On the other hand, giving up Jerusalem and parts of Palestine without need was an unpleasant option for the Sultan.

The drawn-out negotiations brought out Frederick’s best side. He made concessions to the local Barons and Crusaders from other countries by transferring command of troops to his sub-commanders (so that they didn’t have to follow the orders of the excommunicated Emperor) and established a close relationship with the Sultan’s envoy Fahr-ed-Din. Frederick’s knowledge of Arabic and Islamic culture impressed Fahr-ed-Din and the Sultan. Finally, the negotiations started to progress.

This was not what the Pope had hoped. He even sent his envoys to the Sultan, hoping to block Frederick, but they had to leave again without success (yes, the Pope tried to ensure Jerusalem remained in Muslim hands). In February 1229, Emperor and Sultan signed a treaty :

The Sultan and the Crusader States agreed on a ten-year armistice (armistices were a common feature of these treaties).
Jerusalem, Nazareth, and a strip of land from Jerusalem to the coast were surrendered to Frederick.
The Temple Mound in Jerusalem (which included the Dome of the Rock and the Al-Aqsa Mosque) remained under Muslim control.

As a personal favour to the Emperor, he had the right to fortify Jerusalem. Guarantee for the current Christian possessions (Acre, Sidon…) The reasons for this success are lost to history; we can only speculate. It seems that Fahr-ed-Din and the Sultan were impressed by Frederick personally and that the Emperor had shown himself a skillful diplomat, a somewhat unexpected development — within Western Christianity, Frederick’s diplomacy was and always would be lacking. However, the Muslim ruler was too much of a statesman to let personal sympathy sway his judgment. We can also exclude any specific bribes paid by Frederick to Fahr-ed-Din, who remained an essential servant of the Sultan to the end of his life. However, strengthening the Emperor meant weakening the Pope and his allies, the main drivers of the Crusades.

Al-Kamil seems to have reasoned that Christian possession of Jerusalem and ongoing strife between the Emperor and the Pope would keep the Christians away from Outremer. Good relations with Frederick and his successors remained an important feature for the Egyptian Ayyubid Sultans as well as for their successors, the Mamluks. Jerusalem, economically a backwater and a city that would be difficult to be held by the Christians in case of war, was a small price to pay, despite the significant loss of prestige that the Sultan incurred by giving up the city, holy to Muslims as well as to Christians.

The Prelate, representative of the Pope, forbid the pilgrims to follow the excommunicated Emperor, the Knights Templar complained that their original home, the Temple Mount, remained under Muslim control, and the local Barons grumbled that it would be impossible to hold these new possessions. In a way, they were right, but no power would have been able to re-establish the Kingdom of Jerusalem as it had been at its height, regardless of how much money and men were wasted (several Crusades against Egypt prove the point). A treaty like the one Frederick II had made, taking advantage of the rivalry between Muslim rulers, was the best that could be achieved.

The pilgrims, the Emperor and his entourage, and the knights of the Teutonic Order (who was already busy looking for a new base and soon would be fighting against the heathens along the coast of the Baltic) ignored this criticism. They moved in a triumphant procession towards the Holy City. There Fredrick II crowned himself in the Church of the Holy Sepulchre. He had reached his goal — he had conquered Jerusalem, and his army was still intact. He left soon after his coronation, driven away by the hostility of the local Barons and drawn back to Italy by the necessity to defend his possessions from the Pope.

The Aftermath

Due to Frederick’s sudden departure, Jerusalem’s walls were not rebuilt. Makeshift fortifications were sufficient to keep local marauders away, but in 1244 the Khwarazmian Army (refugees from the Mongols, who survived by plundering and serving as mercenaries) swept through the area. They conquered the city quickly and sacked it. Shortly afterwards, Egyptians and Khwarazmians defeated an alliance of Crusaders-States and Syrians near Gaza. After Gaza, the Crusaders States were finished as a political force, although some cities along the coast hung on for more than forty years. The Egyptian Ayyubids occupied Jerusalem itself in 1247. The city now was not much more than a heap of ruins, becoming an unimportant backwater for a long time.

Frederick II returned to Europe and quickly ejected the Pope’s soldiers from his possessions, finally getting his Excommunication lifted in 1230. For the rest of his life, he campaigned in Italy with varying success, only returning to Germany once to suppress his son’s rebellion. His empire did not survive his death in 1250 for long. His natural son Manfred fell in a lost battle in 1266, and Conradin, the last of the Hohenstaufen, was defeated in Italy and beheaded in 1268.

Sultan Al-Kamil profited from the deal — for the rest of his life, he was not bothered by the crusaders and was able to reunify Egypt and Syria shortly before his death in 1238. Afterwards, Egypt remained powerful, but the fortunes of the Ayyubid family declined. The usual infighting of family members allowed the Mamluks (slaves from the Kaukasus and the Steppes, brought at a young age to Egypt and trained as warriors, also often entrusted with administrative duties) to usurp more and more power. Finally, a Mamluk made himself Sultan, deposing the Ayyubids in 1250. The Mamluks beat back the Mongols and tightened their holds on Syria, finally conquering Acre, the last Christian stronghold in Outremer, in 1291.