The crusaders believed their oaths were made invalid when the Byzantine contingent under Tatikios failed to help them during the siege of Antioch ; Bohemund, who had set himself up as Prince of Antioch, briefly went to war with Alexios in the Balkans, but was blockaded by the Byzantine forces and agreed to become Alexios ' vassal by the Treaty of Devol in 1108.

Alexios IV Angelos, the son of the deposed Isaac II, had recently escaped from Constantinople and now appealed to the crusaders, promising to end the schism of East and West, to pay for their transport, and to provide military support to the crusaders if they helped him to depose his uncle and sit on his father's throne.

The crusaders, whose objective had been Egypt, were persuaded to set their course for Constantinople before which they appeared in June 1203, proclaiming Alexios IV as Emperor and inviting the populace of the capital to depose his uncle.

The Fatimids, under the nominal rule of caliph al-Musta ' li but actually controlled by vizier al-Afdal Shahanshah, had lost Jerusalem to the Seljuqs in 1073 ; they recaptured it in 1098 from the Artuqids, a smaller Turkish tribe associated with the Seljuqs, just before the arrival of the crusaders.

John did accompany Frederick to the mainland, but Frederick was not well-received there ; one of his few supporters was Balian, Lord of Sidon, who had welcomed the crusaders the year before and now acted as an ambassador to the Ayyubids.

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.

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.

Damietta was captured without resistance when the crusaders landed in June 1249, but the crusade halted there until November, by which time the Egyptian sultan Ayyub had died and had been succeeded by his son Turanshah.

According to Ellenblum's interpretation the inhabitants of the Kingdom ( Latin Christians living alongside native Greek and Syrian Christians, Shia and Sunni Arabs, Sufis, Bedouin, Turks, Druze, Jews, and Samaritans ) all had major differences between each other as well as with the crusaders.

The Turks were the common enemy for everyone, as they were only very recent arrivals in the Levant, and although they had imposed their rule prior to the arrival of the crusaders, it is unlikely that they were thoroughly Islamicized as Prawer and others believed.

The crusaders were neither totally integrated with the native population, nor did they segregate themselves in the cities away from the rural natives, but rather that they settled in both urban and rural areas ; specifically, they settled in areas that had traditionally been inhabited by the eastern Christians.

The crusaders " had a natural tendency to ignore these matters as simply without interest and certainly not worthy of record.

Greeks, Syrians, and Jews continued to live as they had before, subject to their own laws and courts, with their former Muslim overlords simply replaced by the crusaders ; Muslims now joined them at the lowest level of society.

Jerusalem collected money through tribute payments, first from the coastal cities which had not yet been captured, and later from other neighbouring states such as Damascus and Egypt, which the crusaders could not conquer directly.

The last Estonian county to hold out against the invaders was the island county of Saaremaa, whose war fleets had raided Denmark and Sweden during the years of fighting against the German crusaders.

Innocent III declared that those who took the vow to become crusaders but could no longer perform the tasks that they had promised to complete, they could be released of their oaths by a contribution of funds to the original cause.

In 1224, after additional troops led by prince Vyachko of Kukenois had been installed in the fort, it was besieged and conquered for one last time by the German crusaders.

These men, who had gone to Palestine from Europe either as pilgrims or as crusaders, chose Mount Carmel in part because it was the traditional home of Elijah.

He shared the poor opinion of Alexius I Comnenus that had developed during the First Crusade, although he was also critical of some of the crusaders ' dealings with Alexius.

By mid 1209, around 10, 000 crusaders had gathered in Lyon before marching south.

The crusaders had taken Belcaire and besieged Marmande in late 1218 under Amaury de Montfort, son of the late Simon.

The crusaders heard a rumour that Antioch had been deserted by the Seljuk Turks, so Raymond sent his army ahead to occupy it, offending Bohemond of Taranto who wanted the city for himself.

As there was now nothing the crusaders could do in Syria, they were forced to look to the south if they wanted to expand their territory.

Khalil, believing that the crusaders were negotiating in bad faith, reacted furiously and wanted to kill the two messenger but Emir Sanjar al-Shuja ' pleaded for them and they were sent back to the city.

The Ugaunians wanted to continue the truce with their new neighbors, but the crusaders had a list of preconditions.

The Ugaunians wanted to continue the truce with their new neighbors, but the crusaders had a list of preconditions.

Heinrich von Plauen, new Teutonic Grand Master, wanted to continue fighting and attempted to recruit new crusaders.

A second diversion of the course then occurred when the crusaders decided to conquer Constantinople, the capitol of the Byzantine Empire.

* June 15 – Battle of Lyndanisse: Danish crusaders led by King Waldemar II conquer Tallinn.

Control of Damietta meant control of the Nile, and from there the crusaders believed they would be able to conquer Egypt.

During the Livonian crusade in 1218 Pope Honorius III gave Valdemar II free hands to annex as much land as he could conquer in Estonia, additionally Albert of Riga, the leader of the Teutonic crusaders fighting the Estonians from the south visited the king and asked him to attack the Estonians from the North.

* 1148-Some of the crusaders that had helped King Afonso I of Portugal conquer Lisbon settle in the newly captured city, and Gilbert of Hastings is elected bishop of the renovated Diocese of Lisbon, but most of the crusaders ' fleet continues to the east.

Allegedly, Dietmar boosted the morale of the troops during the crusade: When the enemy had overthrown the flag of the army in Iconium, Dietmar took off his boot and put it onto a lance ; under that sign, the crusaders took new courage and managed to conquer the city.

Jerusalem could now expand only to the southwest, towards Egypt, and in 1153 Ascalon, the last Fatimid outpost in Palestine, fell to the crusaders.

He sent forces to Egypt under the command of Louis I, Duke of Bavaria, but constant expectation of his arrival caused papal legate Pelagius to reject Ayyubid sultan Al-Kamil's offer to restore the Latin Kingdom of Jerusalem to the crusaders in exchange for their withdrawal from Egypt and caused the Crusade to continually stall in anticipation of his ever-delayed arrival.

After hearing of the death of Louis and the evacuation of the crusaders from Tunis, Sultan Baibars of Egypt cancelled his plan to send Egyptian troops to fight Louis in Tunis.

This campaign failed and he was forced to return to Jerusalem, but it provoked Nur ad-Din to lead a campaign of his own against the crusaders in Syria in order to turn their attention away from Egypt.

The crusaders occupied Alexandria and Cairo and made Egypt a tributary state, but Amalric could not hold the country while Nur ad-Din still held Syria, and he was forced to return to Jerusalem.

The crusaders were obliged to pay Venice for sea transport to Egypt.

Pelagius hoped Frederick II would arrive with a fresh army, but he never did ; instead, after a year of inactivity in both Syria and Egypt, John of Brienne returned, and the crusaders marched south towards Cairo in July 1221.

Egypt would, Louis thought, provide a base from which to attack Jerusalem, and its wealth and supply of grain would keep the crusaders fed and equipped.

On 7 May 1099 the crusaders reached Jerusalem, which had been recaptured from the Seljuks by the Fatimids of Egypt only a year before.

In the Holy Land, Philip hoped to take part in a planned invasion of Egypt, for which purpose the crusaders had allied with the Byzantine Empire.

In addition, there is evidence of the Norman crusaders building a motte and bailey using sand and wood in Egypt in 1221 during the Fifth Crusade.

Usama took part in battles with the crusaders outside of Ascalon on his way back to Egypt, and after he left, his brother ' Ali was killed at Gaza.

Saladin eventually succeeded Nur ad-Din as well, uniting Egypt and Syria, which enabled him to almost completely drive out the crusaders from Syria and Palestine.

By the end of his life, however, Syria and Egypt were united under Saladin and had re-conquered most of the Kingdom of Jerusalem from the crusaders.

The Fatimids, assuming the crusaders were simply mercenary representatives of the Byzantines, were prepared to let the crusaders keep Syria if they agreed not to attack Fatimid Palestine, a state of affairs perfectly acceptable between Egypt and Byzantium before the Turkish invasions.

The crusaders had negotiated with the Fatimids of Egypt during their march to Jerusalem, but no satisfactory compromise could be reached — the Fatimids were willing to give up control of Syria but not Palestine, but this was unacceptable to the crusaders, whose goal was the Church of the Holy Sepulchre in Jerusalem.

The crusaders spent the night in the abandoned camp, preparing for another attack, but in the morning they learned that the Fatimids were retreating to Egypt.

In 1248, Louis IX of France went on the Seventh Crusade, but after the defeat of the crusaders, he was captured near Damietta in Egypt.