Additionally, the Sixth Crusade was wildly unpopular among the native Christian leaders because the excommunicated Frederick left them defenseless, allied with their Muslim enemies, and attempted to gain control over the Holy Land for the House of Hohenstaufen rather than restore the territories to the local barons of the Kingdom of Jerusalem.

Rachel suum videns reinforced the usage of a vow of redemption policy initiated by previous Pope Innocent III in his bull Quia maior during his campaign for the Fifth Crusade.

While Italy, Germany, and Spain were mildly enthusiastic about Gregory's crusade, in Hungary, a few nobles and ecclesiastical officials became more actively engaged into the campaign.

[5] About a year later, in December 1235, Gregory began numerous attempts to fully, then partially, redirect this planned crusade away from the Holy Land to instead combat the spread of Christian heresy in Latin Greece.

The Hungarian military elite headed by its king Béla IV declined to go to Constantinople to fight the invading schismatics John III Doukas Vatatzes of Nicaes and Ivan Asen II of Bulgaria.

Simultaneously, Pope Gregory wrote a letter to the Dominicans' prior in Hungary asking him to preach the cross within the empire and exchange the vows for Jerusalem given by crusaders on those to Constantinople in return for indulgence.

[8] The disjointed groups of French barons traveled separately to the Holy Land, where they eventually faced military defeat followed by diplomatic success.

Theobald I, the king of Navarre, gathered an impressive list of European nobles at Lyon, including: Hugh IV, Duke of Burgundy; Amaury de Montfort; Robert de Courtenay the Grand Butler of France (not to be confused with Robert I, Latin Emperor, also from Courtenay); and Peter I, Duke of Brittany.

Finally on 2 November, the group of about 4000 knights (more than half from the local barons and the military orders) marched to Ascalon, where they would begin the construction of a castle which had been demolished by Saladin decades prior.

The Muslims were routed and fled inside the castle, where Peter's men followed them, killed many, took some captives, and seized the booty and edible animals of the caravan.

The leaders of this defiant group were Henry of Bar, Amaury de Montfort, and Hugh of Burgundy, alongside four of the major local lords, including Walter of Brienne, Balian of Sidon, John of Arsuf, and Odo of Montbéliard.

[14] The contingent was soundly defeated before Theobald's forces could arrive to rescue them; Henry was killed, and Amaury was among several hundred crusaders taken prisoner.

After a month of being holed up in the Tower of David, the garrison of the citadel surrendered to Dawud on 7 December, accepting his offer for safe passage to Acre.

[16] After the crusaders' setback at Gaza and the loss of Jerusalem, a civil war within the Muslim Ayyubid dynasty began to create a fortunate environment for the Christians.

The emir Al-Muzaffar II Mahmud of Hama wanted to distract his enemy, Al-Mujahid of Homs, so he lured Theobald's crusaders to Pilgrim Mountain outside of Tripoli with empty promises.

In an act of even more dramatic protest, the Muslim garrison of Beaufort refused to turn over the castle to Balian of Sidon, as Ismail's accord stipulated.

On 23 April 1241 they exchanged Muslim prisoners with Christian captives (most notably Simon's older brother Amaury) who had been seized during Henry of Bar's disastrous raid at Gaza one year and a half earlier.

On July 15, 1244, the Siege of Jerusalem left the city not only captured but reduced to ruins, its Christians massacred by Khwarazmians from northern Syria (new allies of the Sultan of Egypt As-Salih Ayyub).

At the beginning of July in 1239, Baldwin of Courtenay the nineteen-year-old heir to the Latin Empire and Marquis of Namur, travelled to Constantinople with a small army (three times smaller than Barons' Crusade expedition) including the five secular magnates Humbert of Beaujeu, Thomas of Marle, Josseran of Brancion, William of Cayeaux, and Watins of La Haverie.

He continued his way through Germany and Hungary, and at the Bulgarian border, he received a friendly invitation from Ivan Asen II and permission to march through his lands.

However, this victory could not compensate for the loss of two other Asia Minor fortresses, Darivya and Niketiaton (now in the village Eskihisar (tr)) which were captured by Vatatzes.