When Kilij Arslan learnt that the crusaders had besieged Nicaea, he was caught off guard. He hastened back to his army, then marched on Nicaea with the intention to launch a surprise attack on the south wall. Kilij Arslan hid his army in the thickly wooded hills close to the city and, when he thought he could take the enemy by surprise, Kilij ordered his troops to attack.
But the crusaders were not to be fooled: they were fully prepared to engage the Turks in battle. Prior to the Turkish ambush, they had caught a Turkish spy in their camp, forced him to reveal Kilij Arslan’s plans and abandon his sultan under pain of torture. For that reason alone, the crusaders repelled Kilij Arslan, forcing him to retreat and abandon the Turkish garrison.
Faced no longer with the threat from Turks in the surrounding countryside, the crusaders refocused all of their energy on the siege. “Our men hurled the heads of the killed far into the city, that they (the Turks) might be the more terrified thereat,” the Gesta Account suggested. To the Christian warriors, catapulting heads of their enemy’s dead wasn’t enough: they placed some of those heads on spikes and paraded them around the walls in effort to strike greater terror into the hearts of the Turkish garrison, hoping that they will capitulate.
The Turks, though, were not willing to submit: they put up a fierce resistance against the crusaders. In retaliation, they strung up dead Christian warriors along the wall and left them there to rot.
After spending several weeks fighting, unable to breech the thick walls, the crusaders realized that, if they were to capture Nicaea, they had to employ more than one strategy. They had effectively blockaded Nicaea from the outside world, but the west wall was left open, leaving that side of the city open to receive supplies from allies. The crusaders couldn’t scale the walls with ladders as earlier attempts to do so had failed. They also couldn’t bombard the walls with stones using mangonels; they couldn’t find stones large enough to penetrate those walls. So, instead, they bombarded the walls with light missiles while a contingent of troops attempted to undermine the walls by hand.
Another contingent of Christian warriors built a screen, made of oak that boasted a sloping roof. This screen was built to protect them from the onslaught of arrow heads, stones and boiling water or tar. They ran the screen up against the wall and began immediately to undermine the walls. “So they dug to the foundations of the wall and fixed timbers and wood under it and then set fire to it. However, evening had come; the tower had already fallen in the night, and because it was night they could not fight with the enemy. Indeed, during that night the Turks hastily built up and restored the wall so strongly that when day came no one could harm them on that side.” This made the crusaders’ task at hand much more difficult because, faced with an equally formidable foe, they had to imagine a new and better strategy to take Nicaea.
Asbridge, Thomas. The Crusades: The Authoritative History of The War For The Holy Land. Ecco; New York, 2011.
The Gesta Acccount on “The Medieval Sourcebook: The Siege and Capture of Nicaea: Collected Accounts”: http://www.fordham.edu/halsall/source/cde-nicea.asp Fordham University; New York (accessed 19 February 2013).