[15] Medieval rulers were typically crowned on Sundays, but in Baldwin's case 15 July 1174 was chosen instead as it was the 75th anniversary of the First Crusade's seizure of Jerusalem.

[20][21] No new seneschal was appointed for two years, and so the young and sickly king presided over burdensome High Court meetings when the regent was away on military duties or in Tripoli.

She is frequently accused by historians of exploiting her son's condition for self-gain, but Hamilton notes that the contemporary sources, including Baldwin's tutor, William of Tyre, are biased against her.

[24] It is not clear from whom he caught it; medical historian Piers Mitchell concludes that it must have been someone with whom Baldwin had spent a lot of time at a young age, such as a family member, a wet nurse, or another servant, and who did not exhibit easily visible symptoms.

At the suggestion of his mother, the king appointed his loyal and capable maternal uncle, Joscelin of Courtenay, to the office of seneschal and arranged for him to marry a rich heiress, Agnes of Milly.

[29] The change in government signaled a new Frankish approach to the Egyptian ruler Saladin, who had encircled the crusader states during Raymond's regency by conquering Muslim principalities in Syria.

On 1 August, Baldwin and Raymond led the armies of Jerusalem and Tripoli, respectively, in a raid of the Beqaa Valley (modern-day Lebanon), where they defeated the garrison of Damascus, forcing Saladin to abandon his campaign.

[37] Manuel agreed to take part in the invasion in return for the establishment of Byzantine protectorate over the kingdom and restoration of the Orthodox patriarch, Leontius II, in Jerusalem.

[46] The Byzantines sent a war fleet in preparation of the invasion of Egypt[47] but to Baldwin's regret[48] they withdrew because of the uncooperativeness of Philip of Flanders, Bohemond of Antioch, Raymond of Tripoli, and the grand master of the Knights Hospitaller, Roger de Moulins.

The Templars convinced him to build a castle, Chastellet, on the upper Jordan River; he was reluctant because the Franks had promised not to mark that part of the border.

[61] In late August, Baldwin summoned a host to Tiberias to respond to Saladin's siege of Le Chastellet, but the castle fell before the relic of the True Cross could be fetched from Jerusalem to accompany the Christian troops.

[63] He contemplated her marriage to Duke Hugh III of Burgundy, and wrote to the king of France: "To be deprived of the use of one's limbs is of little help to one in carrying out the work of government ...

It is not fitting that a hand so weak as mine should hold power when fear of Arab aggression daily presses upon the Holy City and when my sickness increases the enemy's daring.

[66] Baldwin acted decisively before his kinsmen's armies reached Jerusalem: he arranged for Sibylla to marry a Poitevin knight, Guy of Lusignan.

[68] The historian Steven Runciman speaks of a division already at the beginning of Baldwin's reign between the cautious, diplomatic native barons and the Hospitallers on one side and the "aggressive, militantly Christian" newcomers from Western Europe and Templars on the other.

Hamilton posits that the factions arose only after Sibylla's marriage to Guy and centered on the king's paternal relatives (cousins Raymond of Tripoli and Bohemond of Antioch; stepmother, Maria; and her new family, the Ibelins) and maternal relatives (mother, Agnes; stepfather, Reynald of Sidon; sister, Sibylla; brother-in-law, Guy; uncle, Joscelin; and Raynald of Châtillon), of whom the king supported the latter.

[68] In light of these problems, Baldwin proposed a two-year truce with Saladin, who was glad to accept in order to campaign freely in northern Syria.

[70] To secure Guy's position and prevent the emergence of an alternative claimant, Baldwin had his eight-year-old half-sister, Isabella, solemnly betrothed to the teenage lord of Toron, Humphrey IV, in October 1180.

Isabella was then sent to live at Kerak Castle with the lady of Oultrejourdain, Humphrey's mother, as far as possible from her maternal kin and potential conspirators.

[71] By the terms of the marriage contract, Humphrey ceded Toron to Baldwin, who thus prevented the union of two great fiefs under one vassal and strengthened his position against the count of Tripoli.

[72] Baldwin made use of the truce with Saladin to strengthen the position of his maternal kin, granting Maron and Chastel Neuf to Joscelin and usufruct of Toron to Agnes, while associating Guy and Sibylla with him in public acts.

In July, Baldwin marched with his host to relieve the Muslims' siege of Bethsan, and his outnumbered army won the Battle of Le Forbelet.

[78] Historian Bernard Hamilton attributes the victory to the respect and loyalty commanded by Baldwin,[79] who stayed on the battlefield despite his illness and intense heat.

[80] He proceeded north to fight the Zengids, thereby expanding his realm, while Baldwin led an attack on Saladin's Damascene territory, then on Bosra, before finally laying siege and capturing Cave de Sueth.

[86] Indeed, the great lords of the kingdom, the independent rulers of Antioch and Tripoli, and the grand masters of the military orders refused to cooperate with Guy.

He immediately dismissed Guy from regency and resumed power, as the defense of such a vital fortress and the king's half-sister within it could not be entrusted to the man who had proven unable to command the troops.

When he returned to Jerusalem in late 1184 or early 1185, Baldwin bestowed regency on Raymond of Tripoli, the man whom he had never trusted, but to whom he could find no better alternative.

Pope Alexander III showed little sympathy when writing about Baldwin, declaring leprosy a "just judgement of God", but another school of thought encouraged the faithful to see Christ in the affected.

[113] Muslim historian Imad al-Din al-Isfahani wrote: In spite of illness the Franks were loyal to him, they gave him every encouragement ... being satisfied to have him as their ruler; they exalted him ... they were anxious to keep him in office, but they paid no attention to his leprosy.

[113]Baldwin's public image may have been aided by his chastity, seen as evidence of extraordinary sanctity,[116] and his success against Saladin was interpreted as a sign of God's favor.