sailors, to help with the shipbuilding. A force of arbaletiers was also sent, but the enterprise apparently foundered when the Genoese government ultimately disowned the project, and an internal fight erupted at the Persian Gulf port of Basra among the Genoese (between the Guelph and Ghibelline factions). Fourth mission Arghun sent a fourth mission to European courts in 1290, led by Andrew Zagan (or Chagan), who was accompanied by Buscarel of Gisolfe and a Christian named Sahadin. In 1291, Pope Nicholas IV proclaimed a new Crusade and negotiated agreements with Arghun, Hetoum II of Armenia, the Jacobites, the Ethiopians and the Georgians. On January 5, 1291, Nicholas addressed a vibrant prayer to all the Christians to save the Holy Land, and predicators started to rally Christians to follow Edward I in a Crusade. However, the efforts were too little and too late. On May 18, 1291, Saint-Jean-d'Acre was conquered by the Mamluks in the Siege of Acre. In August 1291, Pope Nicholas wrote a letter to Arghun informing him of the plans of Edward I to go on a Crusade to recapture the Holy Land, stating that the Crusade could only be successful with the help of the "powerful arm" of the Mongols. Nicolas repeated an oft-told theme of the Crusader communications to the Mongols, asking Arghun to receive baptism and to march against the Mamluks. However Arghun himself had died on March 10, 1291, and Pope Nicholas IV would die in March 1292, putting an end to their attempts at combined action. Edward I sent an ambassador to Arghun's successor Gaikhatu in 1292 in the person of Geoffrey de Langley, but extensive contacts would only resume under Arghun's son Ghazan. According to the 20th-century historian Runciman, "Had the Mongol alliance been achieved and honestly implemented by the West, the existence of Outremer would almost certainly have been prolonged. The Mamluks would have been crippled if not destroyed; and the Ilkhanate of Persia would have survived as a power friendly to the Christians and the West" Death Arghun had developed a great interest in alchemy towards end of his reign. He gave shelters to Buddhist lamas who would advice him on religious matters. He also befriended a yogi who claimed to have lived longer than anyone and could offer Arghun the same. The way Rashid al-Din described this alchemist who gave a concoction of sulphur and mercury to Arghun was