Henry I of England was the youngest son of William the Conqueror and succeeded his older brother William II on the throne in 1100. That same year he married a great-granddaughter of earlier English king Edmund II Ironside (tying the old Anglo-Saxon kings to the new Norman ones). Henry was a skilled diplomat and reversed a lot of his unpopular brother William's policies. Their oldest brother Robert, who ruled Normandy, was so unpopular than the Norman subjects revolted and asked for Henry to aid them; Robert was taken prisoner and held in a castle for the rest of his life, and England and Normandy were reunited under one ruler.

Henry's one legitimate son drowned in a shipwreck, leaving only a daughter, Matilda. He made her the heir to the throne in 1126, which was a controversial move -- people weren't sure what to think of the idea of a woman ruling England. Nonetheless, he made many of his barons swear to support her. Henry died on 1 December 1135 of ptomaine poisoning, apparently brought on by a dinner of lampreys. Depsite Henry's intentions, his nephew Stephen seized the throne after his death.