King Baldwin IV of Jerusalem, also known as the Leper King, led one of the most remarkable lives of any medieval monarch. But who was the Leper King?
In 1161, in the Holy City of Jerusalem, a prince was born—Baldwin, the son of Amalric I, King of Jerusalem, and his wife, Agnes of Courtenay. The arrival of a male heir seemed to resolve the dynastic uncertainties that had troubled the kingdom for decades. Amalric was a formidable and successful ruler who had advanced Jerusalem’s interests, and he had a keen interest in chronicling the dynasty’s history. To this end, in 1170, he employed the services of William, later Archbishop of Tyre, to compile a history of the Jerusalemite monarchy. A lasting friendship developed between the two men, and Amalric appointed William as tutor to his young son and heir.
A Tragic Discovery
It was during his tenure as Baldwin’s tutor that William first realised something was amiss with the prince:
“He was playing one day with his companions of noble rank, when they began, as playful boys often do, to pinch each others’ arms and hands with their nails. The other boys cried out in pain, but Baldwin, although his comrades did not spare him, endured it altogether too patiently, as if he felt nothing. After this had occurred several times, it was reported to me. At first, I supposed it was due to his capacity for endurance and not a lack of sensitivity. But when I called him and began to inquire, I discovered that his right arm and hand were partially numb, so that he did not feel pinching or even biting in the least.”
Alarmed, William reported the situation to Amalric, and physicians were consulted. Although leprosy was suspected, a formal diagnosis at this stage would have been unthinkable. Misdiagnosing the heir with an incurable disease could have jeopardised the kingdom.
In 1174, Amalric died unexpectedly, and Baldwin ascended to the throne at just thirteen years old. Already exhibiting symptoms, Baldwin’s coronation went uncontested. Investigations into his condition continued:
“Repeated fomentations, oil rubs, and even poisonous remedies were employed without result in the attempt to help him. For, as we recognised in process of time, these were the premonitory symptoms of a most serious and incurable disease which later became plainly apparent… For, as he began to reach years of maturity, it was evident that he was suffering from the terrible disease of leprosy.”
The phrasing “as he began to reach years of maturity” suggests the diagnosis was confirmed when Baldwin entered puberty, after his coronation. Historians infer that he suffered from lepromatous leprosy—the most severe and contagious form—characterised by loss of eyebrows, deformation of limbs, numbness, and eventual deterioration of fingers, toes, and sometimes sight.
Because Baldwin was still a minor, the kingdom was governed by a regent, a role eventually assumed by his paternal cousin, Count Raymond III of Tripoli. Raymond oversaw the administration and military command of Jerusalem, though Baldwin did not relinquish all responsibilities. Even as a teenager, he participated in raids against Muslim-held territories, honing the military skills expected of a Jerusalemite king.
This training was crucial. Jerusalem was surrounded by hostile forces, and all previous kings had demonstrated exceptional martial ability. Despite his illness and youth, Baldwin was determined to follow in their footsteps. As his left arm was weakened, he learned to ride using his knees, keeping his right arm free to wield a sword.
The Implications of Leprosy
Baldwin’s disease had severe social and political implications. In medieval Western societies, lepers were shunned, considered morally corrupt and divinely condemned, and often banished from communities. They were reliant on charity, unable to marry, work, or participate fully in society.
In contrast, Eastern attitudes were comparatively kinder. Arabic medicine had a more nuanced understanding of the disease, and lepers often lived within communities. The Order of St Lazarus, a military order composed largely of lepers, exemplifies this difference.
For Baldwin, leprosy meant he would never marry or produce heirs, making succession a pressing issue. He had two sisters: Sibylla, his full sister born around 1159, and Isabella, born around 1172 to Amalric and his second wife, Maria. Sibylla became the kingdom’s hope for dynastic continuity.
In 1176, Sibylla married William of Montferrat, nicknamed “Longsword.” The couple conceived a son, but William died in 1177, before seeing his child born. Sibylla named the boy Baldwin after his uncle.
The Battle of Montgisard
That same year, at just sixteen, Baldwin faced his greatest military challenge. Most of his forces had been sent north with Count Philip I of Flanders, leaving the kingdom vulnerable. Saladin, Jerusalem’s formidable Muslim adversary, seized the opportunity and invaded.
Despite his illness, Baldwin led a desperate defence. He raised a small army of several hundred knights, along with the Templars and Hospitallers, against Saladin’s thousands. Knowledge of the terrain and the strategic use of the True Cross before his troops contributed to a decisive victory at Montgisard. Saladin narrowly escaped, reportedly fleeing on a racing camel. This early triumph remained a defining moment in Baldwin’s life.
Later Years and the Succession Crisis
In 1180, Baldwin arranged a second marriage for Sibylla to Guy of Lusignan, a newcomer to the Holy Land whose rapid rise angered the Jerusalemite nobility. By 1183, Baldwin’s leprosy had advanced: his hands and feet were rotting, and he had lost his sight. Now confined to a litter, he attempted to secure a capable regency and succession.
Guy, as Sibylla’s husband, assumed regency but failed to act decisively against Saladin, earning the disdain of both Baldwin and the nobility. Baldwin’s solution was to crown his six-year-old nephew, Baldwin V, as co-ruler on 20 November 1183, with Raymond III as regent for both the boy and the ailing king.
Baldwin IV’s Death and Legacy
Baldwin IV succumbed to leprosy in the winter of 1184 and died in March 1185. His nephew followed in 1186, and the kingdom passed to Guy through Sibylla. The subsequent defeat at the Battle of Hattin in 1187 led to the loss of Jerusalem, and Isabella was later married to maintain claims to the throne.
Despite the physical and political limitations imposed by leprosy, Baldwin IV led a remarkable life. He was a skilled military commander who earned the admiration of both subjects and foes. His determination and strategic prowess secured him a lasting legacy as one of the most extraordinary medieval monarchs.
