Abu al -Qasim Ahmad al - Mustansir bi- llah, and al - Mustansir II (Arabic: أبو القاسم أحمد المستنصر بالله الثاني, DMG Abū al - Ahmad al - Mustansir bi Qāsim llāh - at- Tani, † November 27 1261 ), was the first Caliph of the Abbasid dynasty resided in Cairo.
Al- Mustansir was a nephew of the caliph al - Mustansir I and first cousin of al - Mustasim, the last resident in Baghdad caliphs. He survived the massacre in 1258 of the Abbasids, the Mongol ruler Hulagu had ordered after the conquest of Baghdad. In a roundabout way he came in the summer of 1261 to Cairo, where now the Mamelukensultan Baybars I. reigned.
In June 1261 the Abbasid Abu l - Abbas Ahmad al -Hakim bi- Amrillah (al- Hakim I. ) was proclaimed by a rebellious Mamelukes caliph in Aleppo. Baibars refused this consequence the recognition and proclaimed his hand in Cairo, al - Mustansir caliph. Together with the Sultan al - Mustansir moved in October 1261 to Damascus to the subjugation of Syria tackle. In Damascus he received from Baibars an army of 3000 warriors put aside, with whom he was to go against the Mongols of Hulagu in Mesopotamia. Whether Baibars had it pulled the conquest of Baghdad or just securing the Euphrates into consideration is controversial. However, al -Hakim I had already made a foray up to 20 km before Baghdad.
Al- Mustansir could take several cities along the western Euphratufers. In al - Anbar be a stocked army was discovered by a Mongolian patrol, followed by a larger Mongol army in the night from 26 to 27 November from al - Mustansir unnoticed crossed the Euphrates, and thus introduced him to a fight. Al- Mustansir attacked the Mongols with his infantry and first appeared over the opponent the upper hand to win. In fact, he has run into a case of the Mongols, who had applied its proven tactics of the pretended flight. When the Caliph had removed with his infantry far enough from his cavalry that was asked of Bedouins and Turkomans, reversed the Mongols and surrounded him. Al- Mustansir had no chance against the superior forces and was killed, his head should have been presented by the Mongols in several cities of Iraq, as proof of his defeat. Al- Mustansirs cavalry had made no attempt to save him during the battle, but had immediately fled, so she was assumed in contemporary reports betrayal.
After the death of al - Mustansir be Gegenprätendent al -Hakim I moved to Cairo and received by Sultan Baybars recognition as the rightful caliph.