Not only was his childhood troubled - his father Amalric had been forced to disown his mother Agnes when Baldwin was two years old before the aristocracy would accept him as king, and Baldwin was only 13 when Amalric died and he took the throne - he contracted leprosy at a young age (Baldwin's symptoms are discussed in a useful appendix by Piers Mitchell).

The disease could not be hidden; "It grew more serious each day, specially injuring his hands and feet and his face, so that his subjects were distressed whenever they looked at him," William of Tyre, chief contemporary chronicler of the day, relates.

A lesser person would have quickly broken under such circumstances. But Baldwin was animated by both a bold spirit and a tremendous sense of duty, of his obligation to his people. One of the most human touches is William of Tyre's depiction of Baldwin as "a good looking child for his age" who grew up "full of hope" and "more skilled than men who were older than himself in controlling horses and in riding them at a gallop," (p 43). Baldwin had taught himself this skill, vital to a knight, despite already losing feeling in his right hand. And he continued to ride at the head of his men into battle when there was no way he could have remounted had he been unhorsed. Determination and courage were to be the hallmarks of his all too brief career.

For Baldwin was by any measure a successful king - considering his circumstances and limited resources, a great one. Though his people were massively outnumbered and surrounded on three sides, this boy, who took the throne in 1164 and died aged not quite 24 in 1185, for 11 years frustrated the ambition of Saladin, the greatest warrior of the age, to forge unity among the Arab people and drive the Christians from the Holy Places.

Despite being significantly outnumbered, he defeated Saladin in two major battles, Mont Gisard in 1177 and Le Forbelet in 1182, and forced him to raise the siege of Beirut in 1182 and the major fortress of Kerak twice, in 1183 and 1184. On the latter occasions he was blind and so debilitated he had to be slung in a litter between two horses.

Hamilton also helps untangle the intricate web of domestic and international relations in which Jerusalem, the center of the world for three faiths, was ensnared. Baldwin had to balance the conflicting jealousies and agendas of his own nobility, always maneuvering to secure their positions first in the event of a regency, then at the succession; the knightly orders that were within his kingdom but not of it; the neighboring Crusader states; the attitude of the Papacy; the interests of Byzantium; and the distant and fickle responses of the western European powers. And overshadowing all this was ever-present menace of the Islamic counterattack that could come anytime, anyplace. Given this ever-precarious situation, Baldwin perhaps emerges with even greater credit for his diplomacy than for his skills with the sword. Certainly, he made no fatal mistakes and left the kingdom in no weaker condition than he found it.

Hamilton makes no great departures in his work, but goes some way towards rehabilitating Reynald of Chatillon from his characteristic depiction as loose cannon psychopath. Following Michael Lyons and David Jackson's Saladin: The Politics of Holy War, he also demythologizes the Crusader's nemesis, emphasizing the traditional argument that the Christian state unnecessarily provoked Saladin into war is flawed: The great leader of the Muslim world had been working towards the cleansing Jihad his entire career.

This is a book as much about an era as an individual, and at times, Baldwin as a personality tends to disappear inside it. Even considering the limitations of the sources, one wishes there was more representing his perspective in his voice. But we are limited to a heartfelt letter he wrote to Louis VII of France, humbly recognizing his limitations and offering to hand the kingdom over to a candidate as noble, and more healthy, than he: "To be deprived 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." (p 140).

It was fortunate for the Kingdom of Jerusalem that this offer was refused. It is significant that just two years after Baldwin's death Saladin won his great victory at Hattin, fatally wounding the Crusader presence in the Middle East and setting in motion the chain of events that would culminate in their expulsion in 1291.

"Few rulers have remained executive heads of state when handicapped by such severe physical disabilities or sacrificed themselves more totally to the needs of their people," (p 210) Hamilton concludes. Baldwin's accomplishments would seem to be the stuff of myth, but he was quite real, a testament to human courage and endurance, and Hamilton does a fine job of putting his life and times in perspective.