How important was Muslim disunity to the success of the First Crusade ?

Muslim disunity was the biggest reason for the success of the first crusade. As a nation they were divided in both religious and political aspects. The crusaders had a distinct advantage over the Muslims, strength in numbers. There was basic division in the Islamic faith, Sunni Orthodox controlled Asia Minor and Syria, where their leader was the caliph of Baghdad. The other opposing religious group were know as Shiite. Shiite’s ruled over Egypt through the Fatimid dynasty, who had their own caliph based in Cairo. There was so much bitterness between the two groups that they allied with the crusaders against one another, rather than defend their land together. A jihad was impossible with such disunity. Political turmoil had afflicted both the Sunni and Shiite lands in the 1090’s there were a series of deaths of important Muslim leaders. 1094 especially saw a heavy mortality rate among the caliphs. This year was known as ‘The year of death of caliphs and commanders’. This had a drastic effect on the Muslim people as they no longer had strong leaders to build armies and lead the people. The Muslim world had been one that was now easy to conquer.
In contrast to the powerful rule of the Seljuck Sultan Malikshah who had died in 1092 by 1097-99 there was a power vacuum in Asia Minor and Northern Syria. When crusaders reached the area they were confronted by a series of small rival lordships more concerned with fighting each other than defending the crusade. Leadership of the Sunni world remained in Baghdad, distracted by conflicts closer to home and unconcerned by appeals for help from the distant Levant. For the crusaders it was now easier to defeat opponents in this condition then a strong and well established leader such as Malikshah. If a leader such as Malikshah was still alive during the crusade it is probable that they would’ve failed to cross Asia Minor had they faced such an enemy. Another point to the crusaders advantage was Muslims failed to recognise the crusade as an army of religious colonisation, evidence suggests that they saw it as another raid from the Byzantine Empire rather than an army set on the capture and settlement of land.
However Muslim disunity cannot be attributed wholly to the success of the crusade. Faith was a powerful tool; it can make people push beyond their limits and to achieve unattainable goals, as is stated by Seton and Baldwin ‘without zeal and a burning faith it could never have been achieved' and hence it was definitely a positive factor in helping the success of the crusaders. The crusaders were from all different parts of Europe and spoke many different languages. It was their belief in achieving the one aim of capturing Jerusalem that made them work effectively together as a fighting force. This can be seen when the crusaders captured Antioch. As soon as they captured Antioch, after a gruelling siege of eight months, the crusaders themselves were besieged by an army of Kerbogha of Mosul's. The crusaders were hungry and tired. Furthermore their morale was dangerously low, they were fighting night and day to keep the besiegers out, and just when they thought that all was lost a minor monk called Peter Bartholomew believed he saw a vision of the holy lance and where it had been buried, and took crusaders to the place where the lance was. Once they had retrieved it they believed that God was now on their side. This was enough of a sign to give the crusaders faith that they would win and made them fight on. On June 28th they defeated Kerbogha's forces. This is a prime example to prove that it was their faith which encouraged the Crusaders to go forth and to face the enemy head on instead of giving up. However Asbridge argues was not the most important factor as crusaders took two weeks to attack and they had even tried to contract Kerbogha to surrender and go home but he refused.
Another key factor which can be seen