Partly because of poor planning and coordination - the same reason the “peoples’ crusades”, the first wave of the First Crusade failed - but mostly because they followed the same general route as the First Crusade, and the Turkic states in Anatolia were expecting them and easily destroyed them.
Crusaders who returned home after 1099 inspired another wave of crusaders to leave in 1100-1101. These also included many crusaders who had returned home early before Jerusalem was captured, and were now being shamed in going back, most notably Hugh of Vermandois and Stephen of Blois (both of whom were eventually killed during the new crusade). New crusaders included groups from northern Italy, from Aquitaine and Burgundy in France, and Bavaria and elsewhere in the Holy Roman Empire.
Very briefly, they were supposed to meet up at Constantinople, like the main wave of the First Crusade did, and then continue into Anatolia as a big group. But some of them arrived early and didn’t want to wait, and they were so disruptive to the local economy that Emperor Alexius encouraged them to cross over into Anatolia as quickly as possible. They did, in small groups, and for the most part thee Turks found and them and defeated them all. Some of them made it rather far, as far as Ancyra in central Anatolia, but they didn’t last very long. Other crusaders didn’t continue on foot but sailed to Jerusalem instead.
So why didn’t it work this time?
“…the several armies missed the rendezvous by a very narrow margin of time; this was partly the result of their own behaviour, partly a matter of chance. Separately they fell before a temporary alliance of Moslem princes; together they might have fought their way through to Syria…Their leadership was poor, their knowledge of the enemy’s territory and tactics slight…The crusaders of 1101 had no organization, no system, no luck, and so they set a pattern of failure that was to be followed by those of 1147 and 1190. ” (Cate, pg. 366)
The Seljuks of the Anatolian Sultanate of Rum were busy fighting amongst each other during thee First Crusade, as well as with a neighbouring Turkic state, the Danishmendids, further east in Anatolia. In Syria the various Seljuk emirs didn’t work together at all during the First Crusade. But they realized right away that if they united, they could easily prevent anyone from crossing Anatolia…and so they did. The Crusade of 1101 was stopped because the Muslim states in Anatolia and Syria knew they were coming and remembered their own failures only a few years earlier.
“Westerners did not know that the Turkish princes had been at odds with one another in 1097-8, whereas those in Asia Minor had come together in a league against the crusaders in 1101.” (Riley-Smith, pg. 133)
Another possible reason is that the new crusaders didn’t take it as seriously as the First Crusaders did. Jerusalem had already been captured, so maybe they thought it would be easier to get there, and they treated it more like a regular pilgrimage than a military expedition.
“…there is, perhaps because they were journeying to an already liberated land, perhaps because they believed that their enterprise had already been proved to be so divinely inspired that it could not possibly fail…something more akin to knight-errantry and to the attitudes of their paragons in the chansons than to the dogged pertinacity of the first crusaders.” (Riley-Smith, pg. 129)
Medieval authors, as they usually do, tended to blame any failure on the sins of the crusaders. Perhaps this crusade had to be defeated to humble them, to erase the sin of pride that they felt after conquering Jerusalem.
“It was natural, therefore, for the disasters of 1101 to be considered salutary punishments brought by the participants on their own heads.” (Riley-Smith, pg. 133)
They actually had no idea about the internal divisions and quarrels among the Seljuks, so they assumed that both the First Crusade and the Crusade of 1101 fought the same strong and united Turks. They could admit that 1101 was a failure, but it made the success of the First Crusade even greater and more miraculous.
Some participants blamed the Byzantine Empire again. They blamed the Byzantines for anything that went wrong during the First Crusade too. This time, Emperor Alexios had shuffled them off to Anatolia too quickly, or didn’t give them enough supplies, or abandoned them without any military assistance. From the Byzantine perspective, of course, this was just another massive crowd of people that was rampaging through their own territory! The Byzantine priority was to move them along as fast as they could with as little damage as possible.
“Most of the western writers who describe the Crusade of 1101 accuse the basileus [Emperor Alexios], either directly or indirectly, of betraying the armies of that year to the Turks.” (Gate, pg. 366)
Unfortunately we don’t really know as much about the Crusade of 1101 as we do about the First Crusade. There are a lot of surviving chronicles of the First Crusade, some of which were written by participants, but the only author who participated in 1101 is Ekkehard of Aura. Ekkehard sailed from Constantinople to Jerusalem, so he wasn’t present for the events in Anatolia. We also don’t have as many secondary sources since most modern historians tend to treat it as a footnote to the First Crusade. For example, Thomas Asbridge’s recent history simply summarizes it in less than a page. His conclusion:
“The expedition enjoyed neither the luck nor the hard-bitten unity of purpose that had characterised the First Crusade. It was ripped apart by the Seljuqs of Asia Minor, suffering horrific casualties, and those few who did reach the Holy Land achieved nothing of value.” (Asbridge, pg. 330)
Sources:
Thomas Asbridge, The First Crusade: A New History (Oxford University Press, 2004)
Jonathan Riley-Smith, The First Crusade and the Idea of Crusading (University of Pennsylvania Press, 1986), specifically Chapter 5, “The Crusade of 1101”, pg. 120-34
J. L. Cate, “The crusade of 1101”, in A History of the Crusades, vol 1: The First Hundred Years, ed. M. W. Baldwin (University of Wisconsin Press, 1969), pp. 343-67.