Isabella I of Jerusalem tried to play Isabella and her husband off against him, but Humphrey did homage to the royal couple. Isabella was the daughter of Amalric, King of Jerusalem, by his second wife, Maria Comnena. Maria Comnena (who was a grandniece of the Byzantine Emperor, Manuel I Komnenos) married Amalric on 29 August 1171. Isabella was born before September 1172. Amalric died unexpectedly on 11 July 1174. His son by his first marriage, Baldwin IV, was crowned king two weeks later. Before long, it became obvious that Baldwin suffered from lepromatous leprosy. To secure the succession of the ailing king, his sister,
Baldwin of Avesnes Baldwin of Avesnes Baldwin of Avesnes (September 1219 in Oizy – 10 April 1295 in Avesnes) was a son of Bouchard IV of Avesnes and his wife, Margaret II of Flanders. His parents' marriage was later declared illegal, because his father had already received minor orders. Baldwin was later declared legitimate by the pope, at the instigation of King Louis IX of France. In 1246, Baldwin received Beaumont as an apanage. He fought his whole life, together with his brother John I, against his half-brothers from his mother's second marriage with William II of Dampierre. He was said to be