Oengus' Crusade
High King Oengus was an unlikely crusader. A popular account has him replying to a monk who asked him whether his skeptical attitude would damn him to hell, "If God knows all, then he knows why men doubt." He was not an outright atheist, and would make expected appearances at mass on important occasions. He supported the Church in Ireland, mostly for practical reasons such as their social services and educational monopoly. But he also employed more non-clerical scribes in his government than his predecessors, fatefully including his court historian, Muireadhach Albanach Ó Dálaigh. Actually born in Scotland, O'Dalaigh fled to Ireland as a consequence of a murder he committed in his own country, and rose to favor through his learning and prodigious memory. While his predecessors had mainly been concerned with the past, O'Dalaigh wrote principally about current events, and accompanied the High King on his crusade. His
Pilgrimage of the High King, while undoubtedly primarily a work of propaganda, is a rare first-person account committed to writing by a man who was either an eyewitness or had access to those who were.
According to O'Dalaigh, "the learned monk [who had delivered word of the call to Crusade] had not finished speaking before the High King ordered his hosts to gather." O'Dalaigh suggests that the High King was motivated by a desire to hedge his bets. If his more righteous relatives were right and he was damning himself with skepticism, he would "pay the Lord an honor price in heathen blood." Alternative explanations have been offered ever since. He may have worried that his rivals in Scotland might try to turn the church against him. He might have hoped for lands or plunder, or felt the need to keep his numerous and warlike subjects busy.
In any case, he did indeed amass a large force. O'Dalaigh claims that he gathered 18,000 troops, a figure notable for being plausible (most medieval sources tending to drastically overstate numbers), spread between 230 ships. Included in this figure was a strong contingent of Teutonic Knights, whose Hochmeister happened to be an aged member of the O'Dea clan. 8,000 of these were allegedly Galloglaigh or native Irish similarly armed. 900 (including the Teutons) were knights, with 2 squires each. The remaining troops were kerns, common foot soldiers fighting either as light infantry or archers. They sailed easily through the straight of Gibraltar, benefiting from the decline in Muslim power there at the hands of the rising Fadlid dynasty, and made landfall in the holy land at Arsuf in late September 1126
By the time the Irish crusaders arrived, a mixed force of Italian, German and Frankish crusaders had arrived overland via the Byzantine Empire. They had clashed with the Caliphate's forces in Syria, working their way south along the coast as far as Acre. Combined this force was slightly larger than the Irish army. It had defeated the Muslim army in the region, the shattered remnants of which were only slightly inland. The Caliph was further weakened by a rebellious Emir to the south who had chosen this time to break ties with his overlord, which would delay the mustering of reinforcements from Egypt.
As a military campaign, Oengus' invasion would be somewhat anticlimactic. His Irish forces fought no field actions against anything approaching an equal force. While his soldiers implored the High King to make a dash for the seemingly vulnerable holy city, Oengus insisted on securing his supply lines. Rather than take the cities and fortresses in his path by bloody, righteous assaults as St Orlaith would have, Oengus lay methodical sieges. He starved the enemy, undermined defenses, and only took the leash off his ferocious warriors when he felt the odds were decisively in his favor. His primary concern was with water and food. The Pilgrimage of the High King describes more clashes with frustrated members of his own army than battles with the enemy. It took his army most of two months to travel the short distance from Arsuf to Jerusalem. But in that time Oengus isolated and captured every Muslim stronghold, secured every well, and secured his supply lines back to his fleet.
On November 17, 1128, Oengus' forces had assembled three siege towers, and the High King gave his consent for the final assault. The Teutonic Order claimed one of the siege towers, assaulting the walls to capture the Golden Gate, with one Irish force to stage a diversionary attack at the St Stephen's (or Damascus) gate, and the main Irish force to assault David's Gate. According to O'Dalaigh, the Crusaders disagreed about who was the first over the wall, and which assault could claim to have taken their objective first. Oengus' personal Corrughadh of Knights were the first to raise the standard of the Irish crusaders (a green St Patrick's cross) over the temple mount.
O'Dalaigh writes that 43 knights and 398 galloglaigh died in the final assault. The number of dead on the opposing side is unclear. Certainly the garrison was killed to a man, and many civilians killed in the assault. Oengus, already with his eye on the future viability of Christian rule in the city, forbade and punished looting of public buildings, and insisted that Muslims hiding in Mosques be allowed to surrender safely. Private residences and shops were certainly pillaged, and the Muslim population indisputably shrank. The question of just how many innocent civilians were killed has since become highly politicized, used as a justification and accusation against various groups.
in any case, November 18 dawned on a Jerusalem under the rule of the High King of Ireland.