Editing Kingdom of Jerusalem (section)

=== War of the Lombards and the Barons' Crusade ===
{{Main|War of the Lombards}}
[[File:JanBrienne.jpg|thumb|Coronation of [[Maria of Montferrat]] and [[John of Brienne]], King of Jerusalem and [[Latin Emperor of Constantinople]]]]
Nevertheless, Frederick [[War of the Lombards|sent an Imperial army]] in 1231, under Richard Filangieri, who occupied Beirut and Tyre, but was unable to gain control of Acre. John's supporters formed a [[Commune of Acre|commune in Acre]], of which John himself was elected mayor in 1232. With the help of the [[Genoa|Genoese]] merchants, the commune recaptured Beirut. John also attacked Tyre, but was defeated by Filangieri at the [[Battle of Casal Imbert]] in May 1232.{{Sfn|Edbury|1991|pp=57–64}}

In Cyprus, King Henry I came of age in 1232 and John's regency was no longer necessary. Both John and Filangieri raced back to Cyprus to assert their authority, and the imperial forces were defeated at the [[Battle of Agridi]] on June 15. Henry became the undisputed king of Cyprus, but continued to support the Ibelins over the Lusignans and the imperial party. On the mainland, Filangieri had the support of [[Bohemund IV of Antioch]], the [[Teutonic Knights]], the [[Knights Hospitaller]], and the [[Pisa]]n merchants. John was supported by his nobles on Cyprus, and by his continental holdings in Beirut, [[Caesarea Maritima|Caesarea]], and [[Arsuf]], as well as by the [[Knights Templar]] and the Genoese. Neither side could make any headway, and in 1234 Gregory IX excommunicated John and his supporters. This was partly revoked in 1235, but still no peace could be made. John died in 1236 and the war was taken up by his son [[Balian of Beirut]] and his nephew [[Philip of Montfort, Lord of Tyre|Philip of Montfort]].{{Sfn|Tyerman|2006|pp=725–726}}

Meanwhile, the treaty with the Ayyubids was set to expire in 1239. Plans for a new crusade to be led by Frederick came to nothing, and Frederick himself was excommunicated by Gregory IX again in 1239. However, other European nobles took up the cause, including [[Theobald I of Navarre|Theobald IV]], [[Count of Champagne]] and [[King of Navarre]], [[Peter I, Duke of Brittany|Peter of Dreux]], and [[Amaury de Montfort (died 1241)|Amaury de Montfort]], who arrived in Acre in September 1239. Theobald was elected leader of [[Barons' Crusade|the crusade]] at a council in Acre, attended by most of the important nobles of the kingdom, including [[Walter IV of Brienne|Walter of Brienne]], [[John of Arsuf]], and [[Balian Grenier|Balian of Sidon]]. The arrival of the crusade was a brief respite from the Lombard War; Filangieri remained in Tyre and did not participate. The council decided to refortify Ascalon in the south and attack Damascus in the north.

The crusaders may have been aware of the new divisions among the Ayyubids; al-Kamil had occupied Damascus in 1238 but had died soon afterwards, and his territory was inherited by his family. His sons [[al-Adil II|al-Adil abu Bakr]] and [[as-Salih Ayyub]] inherited Egypt and Damascus. Ayyub marched on Cairo in an attempt to drive out al-Adil, but during his absence al-Kamil's brother [[As-Salih Ismail, Emir of Damascus|as-Salih Isma'il]] took over Damascus, and Ayyub was taken prisoner by an-Nasir Dawud. The Crusaders, meanwhile, marched to Ascalon. Along the way, Walter of Brienne captured livestock intended to resupply Damascus, as the Ayyubids had probably learned of the Crusaders' plans to attack it. The victory was short-lived, however, as the Crusaders were then defeated by the Egyptian army at Gaza in November 1239. [[Henry II, Count of Bar]] was killed and Amaury of Montfort captured. The Crusaders returned to Acre, possibly because the native barons of the kingdom were suspicious of Filangieri in Tyre. Dawud took advantage of the Ayyubid victory to recapture Jerusalem in December, the ten-year truce having expired.

Although Ayyub was Dawud's prisoner, the two now allied against al-Adil in Egypt, which Ayyub seized in 1240. In Damascus, Isma'il recognized the threat of Dawud and Ayyub against his own possessions, and turned to the Crusaders for assistance. Theobald concluded a treaty with Isma'il, in return for territorial concessions that restored Jerusalem to Christian control, as well as much of the rest of the former kingdom, even more territory than Frederick had recovered in 1229. Theobald, however, was frustrated by the Lombard War, and returned home in September 1240. Almost immediately after Theobald's departure, [[Richard, 1st Earl of Cornwall|Richard of Cornwall]] arrived. He completed the rebuilding of Ascalon, and also made peace with Ayyub in Egypt. Ayyub confirmed Isma'il's concessions in 1241, and prisoners taken at Gaza were exchanged by both sides. Richard returned to Europe in 1241.<ref>Michael Lower, ''The Barons' Crusade: A Call to Arms and its Consequences'' (University of Pennsylvania Press, 2005), pp. 159–177.</ref>

Although the kingdom had essentially been restored, the Lombard War continued to occupy the kingdom's nobility. As the Templars and Hospitallers supported opposite sides, they also attacked each other, and the Templars broke the treaty with the Ayyubids by attacking Nablus in 1241. Conrad proclaimed that he had come of age in 1242, eliminating both Frederick's claim to the regency and the need for an imperial guardian to govern in his place, although he had not yet turned 15, the age of majority according to the customs of Jerusalem. Through Conrad, Frederick tried to send an imperial regent, but the anti-imperial faction in Acre argued that Jerusalem's laws allowed them to appoint their own regent. In June the ''Haute Cour'' granted the regency to Alice of Champagne, who, as the daughter of Isabella I, was Conrad's great-aunt and his closest relative living in the kingdom. Alice ordered Filangieri to be arrested, and along with the Ibelins and Venetians, besieged Tyre, which fell in July 1243. The Lombard War was over, but the king was still absent, as Conrad never came to the East. Alice was prevented from exercising any real power as regent by Philip of Montfort, who took control of Tyre, and Balian of Beirut, who continued to hold Acre.{{Sfn|Tyerman|2006|pp=725–726}}