鲍德温四世(Baldwin IV of Jerusalem)，(1161年 – 1185年) ，耶路撒冷王国国王，耶路撒冷的阿马里克一世（AmalricⅠof Jerusalem）与库尔特奈的阿格尼丝（Agnes of Courtenay）之子，即位于1174年。即位初期，的黎波里伯爵雷蒙德被选为摄政，王国内分为两派。以雷蒙德、医院骑士团、西顿的雷纳德、伊柏林家族和托伦的杰弗里等本地骑士为一方，以圣殿骑士团和库尔特奈（Courtenay）和吕西尼昂家族（Lusignan）等新来的骑士为另一方，1175年，安条克的雷纳德和乔瑟林从阿勒颇被释放回来，也加入了这一方。患麻疯病的鲍德温在两派之间调停，保持着王国的稳定。
1177年在蒙吉萨（Montgisard），16岁的鲍德温四世率领几百名骑士和数千步兵击败了萨拉丁的三万士兵。
撒拉丁的三万骑兵分成两路发动进攻，其中两万进攻圣殿骑士团所在的加沙地带，一万包围阿斯卡伦。
耶路撒冷几乎没有任何准备，一开始就被打了个措手不及。他们事前甚至没有得到什么情报，结果是在敌军到达阿斯卡伦之前，竟然让国王在少数部队的陪同下到了那个地方，自动把羊羔送到饿虎的嘴边。
塞尔柱人很快就清楚了耶路撒冷王正被他们围困在阿斯卡伦。欣喜若狂的撒拉丁马上组织部队对该地区进行猛烈的攻击，誓要生擒敌酋。国王的骑士卫队镇定地保卫在君主的周围，抱定了进行最后死战的决心。然而这时候，他们却从身后的孩子口中听到了冷静清醒而又条理清晰的指令。骑士们惊奇地转身看着国王，然后鞠躬并举剑示意，执行命令。
在打退塞尔柱人的进攻后，鲍德温抓住对方组织攻势的间隙，率领帐下突围而走。撒拉丁闻讯大发雷霆并派遣马木留克骑兵卫队狂追，但是无济于事。
鲍德温突围后并不向耶路撒冷撤退，他派出通讯员命令各地骑士立即前来与他相会，同时往医院骑士团的驻地进发。在那里，他与带领圣殿骑士团残部突围的雷纳德相遇。狼狈的雷纳德原以为被围的国王已经提前归天，想不到国王已经在部署决战的事宜。他第一次感到那个银面具下所散发的气度，也第一次认识到了国王的权力和威严。于是，耶路撒冷国王集结主力军队，与同样收束军队前来夺取耶路撒冷的撒拉丁在蒙吉萨相遇。
11月25日，双方大战。结果以撒拉丁的溃败而告终，其马木留克近卫部队几乎全灭。
这次大败使撒拉丁退回东边，修养部队。然而战争天才不甘心败在一个弱冠麻风病人的手里。休息一年后，1179年，撒拉丁率军偷袭了在泉水谷的雷纳德和圣殿骑士团，鲍德温闻讯马上亲提大军前来交战。
双方对峙许久，撒拉丁无法占到便宜。于是双方缔结两年的休战协议。沙漠之王终于被拒绝在耶路撒冷国土之外。
由于鲍德温的病情恶化，骑士们决定给他的姐姐西比拉（Sibylla）找一个丈夫，作为王位继承人。他们选择了蒙特费拉特的威廉，但威廉未能成婚，就于1177年初死了。1180年，西比拉爱上了一个来东方冒险的年轻骑士、吕西尼昂的居伊（Guy of Lusignan），二人于复活节完婚。由于雷蒙德摄政反对这门婚事，居伊作为王储，加入了另一派。
鲍德温国王的病情不断恶化，他失明了，时常发烧，身体也在腐烂。1183年，他将摄政权交给了他的姐夫居伊。1183年居伊开始公开不服从国王。鲍德温剥夺了居伊在雅法和阿斯卡德的领地，1185年他指定自己年幼的外甥，西比拉和蒙特费拉特的威廉之子蒙特费拉特的鲍德温为王储，雷蒙德伯爵为摄政，并禁止居伊参与权力，3月鲍德温四世去世。
在鲍德温四世去世后，围绕着王位继承，国内发生了一次重大的冲突。
关于Baldwin的传说和史实：
当Baldiwin IV 陛下生下来接受洗礼之时，当时他的叔父BaldwinIII作为孩子的教父参与主持洗礼。有一位议厅的贵族笑着问国王除了把自己名字给予这个孩子之外，还正式准备了什么洗礼的礼物.
结果Baldwin III看着圣十字架，大笑回答：‘圣地王国！（THE KINGDOM OF Jerusalerm！）所有在场的人都记下这刻。当时正当盛年的国王根本就没有想过自己后嗣的问题。
但是事实确实是，一年之后当Baldwin III国王忽然去世，他兄弟后来的阿莫利一世能之所以能获得王位，除了因为他本身地位，最高议廷也因为尚在襁褓中王子--他被前任国王所给予许诺和王国继承人的地位。
王子幼年时和伙伴玩征战游戏，结果就被他老师william of TYre 发现左手臂毫无痛觉，经过医治诊断后确认是麻风，如果说开始为了安定人心，尚还保密，但十岁时，这些最高议厅的所有人员甚至贵族全部都很清楚！而且他十三岁即位时，他的病症已经很明显了。
但即使这样，当初阿莫利国王远征埃及，染上时疫。没等回到圣地就去世了，他当时也没有留下明确的遗言。消息传来，最高议厅马上举行了会议，提议Baldwin王子继承王位。根据当时记载无一人反对！
所以阿莫利国王去世仅仅四天，就为博杜文王子举行了加冕仪式！当时王子只有十三岁，连王国中不成文规定十五才能继承爵位的年纪都不到！
做为罗马教廷那边，考虑到一个患有神灵惩罚之症的少年成为圣地的君主？那它还有什么言辞来劝告信徒？当然争论很大，并把这种压力传回王国，但是圣地王国除了最高议厅根本不加理会，连当地各大主教（提尔大主教）都回复说国王已经是涂圣油之王，请不要置疑主的世间权威和决定！”
因为刚即位的国王未到法定的年纪，所以只得任命摄政王，先后两位，尤其是雷蒙德伯爵摄政之前时，他还专门和最高议廷签了一纸保证的文书。除了宣誓自己忠诚之外，因为担心伯爵效仿他国对于麻风的习俗，作出失礼的行为。其中还附加了一条，不得在在国王面前提及他的病症！
所以Baldwin 加冕是在最高议廷，各大教区，所有贵族百姓，都知道他们王子Baldwin将来出现于臣民面前的国王，现在年幼无法执政。而将会是会被麻风腐蚀身体，会毁容，会残疾，会盲目，虚弱之下连签署公文都无法，甚至不会有后嗣！可他们都不曾有过犹豫地确认对他的效忠。
关于Baldwin IV 除了他出生，他叔父耶路撒冷王国的许诺，还有绿十字的传说。一说，在他的加冕时，忽然还有一只老鹰飞入加冕的礼堂。张开双翼落在主教正要加冕的王冠之上，正好形成十字于冠上。
一说就是他做梦梦见的绿色十字于手边。至今这个绿十字的标志都保留在国际麻风防止协会的旗帜上。
……
这里是一读者看了他的传记《The Leper King and his Heirs》写下的一介绍。几乎还是不错，可以看看我很欣赏她最后的话，意思大概就是：博杜文的事迹看似神话传说，但是它是真的。它是一份
关于人类勇敢和忍耐力的遗产
Baldwin IV, king of the Crusader Kingdom of Jerusalem is largely - and unfairly - unknown in the west today. But, as Bernard Hamilton details in The Leper King and his Heirs, he deserves so much better. For a start, he accomplished so much more than his famous Crusading near contemporary Richard the Lionheart, and under infinitely more trying conditions.
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 is 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 is 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.
