He is noted for his opposition to the rise ofShajar al-Durr to the Egyptian throne during the Seventh Crusade. He sent a message from Baghdad to the Mamluks in Egypt that said: "If you do not have men there tell us so we can send you men.".[1] However, Al-Musta'sim had to face the greatest menace against the caliphate since its establishment in 632, the invasion of the Mongol forces that, under Hulagu Khan, had already wiped out any resistance in Transoxiana and Khorasan. In 1255/1256 Hulagu forced the Abbasid to lend their forces for the campaign againstAlamut.