http://en.wikipedia.org/wiki/Siege_of_Baghdad_%281258%29 Prior to laying siege to Baghdad, Hulagu easily destroyed the Lurs, and his reputation so frightened the Assassins that they surrendered their impregnable fortress of Alamut to him without a fight in 1256. He then advanced on Baghdad.
Mongke Khan had ordered his brother to spare the Caliphate if it submitted to the authority of the Mongol Khanate. Upon nearing Baghdad, Hulagu demanded surrender; the caliph, Al-Musta'sim, refused. By many accounts, Al-Musta'sim had failed to prepare for the onslaught; he neither gathered armies nor strengthened the city's walls. Even worse, he greatly offended Hulagu Khan by threats he made, and thus assured his destruction.[7]
Hulagu positioned his forces on both banks of the Tigris River, dividing them to form a pincer around the city. The caliph's army repulsed some of the forces attacking from the west, but were defeated in the next battle. The attacking Mongols broke some dikes and flooded the ground behind the caliph’s army, trapping it. Thus were many troops slaughtered or drowned.
The Chinese contingent then laid siege to the city starting January 29, constructing a palisade and ditch, and employing siege engines and catapults. The battle was swift by siege standards: by February 5 the Mongols controlled a stretch of the wall. Al-Musta'sim begged to negotiate, but was refused.
On February 10, Baghdad surrendered. The Mongols swept into the city on February 13 and began a week of massacre and destruction.
[edit] Destruction
Hulagu (left) imprisons Caliph Al-Musta'sim among his treasures to starve him to death. Medieval depiction from "Le livre des merveilles", 15th century.
Many historical accounts detailed the cruelties of the Mongol conquerors.
* The Grand Library of Baghdad, containing countless precious historical documents and books on subjects ranging from medicine to astronomy, was destroyed. Survivors said that the waters of the Tigris ran black with ink from the enormous quantities of books flung into the river and red from the blood of the scientists and philosophers killed.
* Citizens attempted to flee, but were intercepted by Mongol soldiers who killed with abandon. Martin Sicker writes that close to 90,000 people may have died (Sicker 2000, p. 111). Other estimates go much higher. Wassaf claims the loss of life was several hundred thousand. Ian Frazier of The New Yorker says estimates of the death toll have ranged from 200,000 to a million.[8]
* The Mongols looted and then destroyed mosques, palaces, libraries, and hospitals. Grand buildings that had been the work of generations were burned to the ground.
* The caliph was captured and forced to watch as his citizens were murdered and his treasury plundered. According to most accounts, the caliph was killed by trampling. The Mongols rolled the caliph up in a rug, and rode their horses over him, as they believed that the earth was offended if touched by royal blood. All but one of his sons were killed, and the sole surviving son was sent to Mongolia, where Mongolian historians report he married and fathered children, but played no role in Islam thereafter (see Abbasid: The end of the dynasty).
* Hulagu had to move his camp upwind of the city, due to the stench of decay from the ruined city.
Baghdad was a depopulated, ruined city for several centuries and only gradually recovered some of its former glory.
[edit] Comments on the destruction
"Iraq in 1258 was very different from present day Iraq. Its agriculture was supported by canal networks thousands of years old. Baghdad was one of the most brilliant intellectual centers in the world. The Mongol destruction of Baghdad was a psychological blow from which Islam never recovered. Already Islam was turning inward, becoming more suspicious of conflicts between faith and reason and more conservative. With the sack of Baghdad, the intellectual flowering of Islam was snuffed out. Imagining the Athens of Pericles and Aristotle obliterated by a nuclear weapon begins to suggest the enormity of the blow. The Mongols filled in the irrigation canals and left Iraq too depopulated to restore them." (Steven Dutch)
"They swept through the city like hungry falcons attacking a flight of doves, or like raging wolves attacking sheep, with loose reins and shameless faces, murdering and spreading terror...beds and cushions made of gold and encrusted with jewels were cut to pieces with knives and torn to shreds. Those hiding behind the veils of the great Harem were dragged...through the streets and alleys, each of them becoming a plaything...as the population died at the hands of the invaders." (Abdullah Wassaf as cited by David Morgan)
[edit] Causes for agricultural decline
Some historians believe that the Mongol invasion destroyed much of the irrigation infrastructure that had sustained Mesopotamia for many millennia. Canals were cut as a military tactic and never repaired. So many people died or fled that neither the labor nor the organization were sufficient to maintain the canal system. It broke down or silted up. This theory was advanced by historian Svatopluk Souček in his 2000 book, A History of Inner Asia and has been adopted by authors such as Steven Dutch.
Other historians point to soil salination as the culprit in the decline in agriculture.[9][10]
[edit] Aftermath
The year following the fall of Baghdad, Hulagu named the Persian Ata al-Mulk Juvayni governor of Baghdad, Lower Mesopotamia, and Khuzistan. At the intervention of the Mongol Hulagu's Nestorian Christian wife, Dokuz Khatun, the Christian inhabitants were spared.[11][12] Hulagu offered the royal palace to the Nestorian Catholicos Mar Makikha, and ordered a cathedral to be built for him.[13]