Guy laid siege to Acre, but James of Avesnes, Louis III of Thuringia and other crusader commanders who came to the Holy Land also questioned his claim to leadership. Guy's wife, Sybilla, and their two daughters died in autumn 1190. Guy's opponents argued that he had only been king by marriage, and his wife's half-sister, Isabella, inherited the crown. Guy did not want to abandon his claim to the Kingdom of Jerusalem. Taking advantage of the situation, Conrad of Montferrat decided to marry Isabella. Isabella's stepfather supported Conrad's plan. Isabella resisted, but her mother put her under pressure. Maria Komnena also swore that Baldwin IV had forced the eight-year-old Isabella to marry Humphrey of Toron, whose effeminacy was well known. Before long, the papal legate, Ubaldo Lanfranchi, Archbishop of Pisa, and Philip of Dreux, Bishop of Beauvais, annulled the marriage of Isabella and Humphrey. Baldwin of Forde, Archbishop of Canterbury, forbade her to marry Conrad, stating that both Isabella and Conrad would commit adultery if they married. However, Baldwin of Forde died on 19 November 1190. Conrad married Isabella on 24 November. Isabella returned Humphrey the Lordship of Toron that Baldwin IV had annexed to the crown in 1180. Guy of Lusignan refused to abdicate, but most barons regarded him the lawful monarch. Conrad and Isabella returned to Tyre. After Philip II of France, who landed at Acre on 20 April 1191, acknowledged Conrad's claim to Jerusalem, Guy of Lusignan and Conrad's opponents (including Humphrey of Toron and Bohemond III of Antioch) sought assistance from Richard I, King of England, who decided to support them. Guy adopted the title of "king-elect of Jerusalem" in May. The crusaders captured Acre on 11 July 1191. On 28 July, Richard of England and Philip of France agreed that Guy could retain the title of king till the end of his life, but Conrad would rule Tyre, Beirut and Sidon; after Guy's death, the kingdom would be united under the rule of Conrad and Isabella or their issue. Three days later, Philip of France left for France and Richard of England became the sole supreme commander of the crusaders. The native barons remained hostile towards Guy.