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,
Philip I, Count of Flanders brother-in-law, intervened in 1184 on behalf of his son-in-law, King Philip, in support of his daughter's interests. The dispute between Count Philip and Baldwin was encouraged by King Philip, who went so far as to name Baldwin his representative in negotiations with the Count. Count Philip's wife, Elisabeth, died in 1183, prompting King Philip II to seize the province of Vermandois on behalf of Elisabeth's sister, Eleonore. Philip then remarried, to Matilda, daughter of Afonso I, the first King of Portugal. Philip gave Matilda a dower that included a number of major Flemish towns, in an apparent slight to Baldwin