Saladin, the Ayyubbid sultan of Egypt and Syria, laid siege to Kerak during the wedding, but Baldwin IV and Raymond III of Tripoli relieved the fortress.

The barons, who did not want to acknowledge the right of Baldwin V's mother, Sybilla, and her husband, Guy of Lusignan, to inherit the kingdom, decided to proclaim Humphrey and his wife king and queen.

[9] According to the marriage contract, Humphrey renounced his inherited domains (Toron, Banias and Chastel Neuf) in favor of Baldwin IV, in exchange for a money fief of 7,000 bezants.

[9][11] This provision of the marriage contract suggests that the king wanted to prevent Humphrey from uniting two large fiefs, Toron and Oultrejourdan.

[17] During the wedding, Saladin laid siege to the fortress to take revenge for Raynald of Châtillon's plundering raid on the Red Sea in February.

[18] According to a version of Ernoul's chronicle, Humphrey's mother convinced Saladin not to bombard the tower in which the newly married young couple were lodged, although he continued to besiege the rest of the fortress.

[21] The High Court of Jerusalem also decreed that if Baldwin V died, the pope, the Holy Roman emperor, and the kings of France and England were to decide whether Sybilla or Isabella was entitled to succeed him.

[23][24] Sybilla's maternal uncle, Joscelin III of Courtenay, persuaded Raymond of Tripoli to leave Jerusalem to hold an assembly in Tiberias for the barons of the realm.

[29] Before long, acting on Raymond of Tripoli's proposal, the barons at Nablus decided to proclaim Isabella and Humphrey queen and king against Sybilla and Guy.

[33] Humphrey's stepfather, Raynald of Châtillon, plundered a caravan moving from Egypt to Syria in early 1187, claiming that the truce between the Kingdom of Jerusalem and Saladin did not cover his Lordship of Oultrejourdan.

[34] After Guy of Lusignan failed to persuade Raynald to pay compensation, Saladin proclaimed a jihad (holy war) against the Kingdom of Jerusalem.

[50] The contemporaneous Itinerarium Regis Ricardi describes Humphrey, around 1190, as "more like a woman than a man, gentle in his dealings and with a bad stammer".

[48] Ubaldo Lanfranchi, Archbishop of Pisa (who was Papal legate), and Philip of Dreux, Bishop of Beauvais, annulled Humphrey's marriage to Isabella.

[48][52] During an inquiry ordered by Pope Innocent III into the prelates' decision, a group of knights who were present at the proceedings stated that both Isabella and Humphrey had protested the annulment.

[48][52] Humphrey was among the barons who accompanied Guy of Lusignan, who did not renounce the kingdom, to meet King Richard I of England in Limassol in Cyprus in May 1191.

[51] Richard dispatched Humphrey, who was fluent in Arabic, to open negotiations with Saladin's brother, Al-Adil, in Lydda (now Lod in Israel).

[56] Although one of them confessed that Rashid ad-Din Sinan, head of the Assassins, had sent them to kill him, Humphrey was one of the suspects accused by contemporaneous sources of hiring them.

[53] In 1229, Humphrey's patrimony, Toron, was restored to the Kingdom of Jerusalem in accordance with the treaty of Al-Kamil, sultan of Egypt, and the Holy Roman emperor, Frederick II.