I only learnt about this episode in Bizarre European History today, but I wondered why the other Spaniards didn't retalliate, let alone the ruler of Galicia at the time!
The contemporary account of the event that would later be incorporated in the 13th cxentury saga narratives on Sigurd's expedition to the Holy Land is a stanza of the eulogy poem to King Sigurd of Norway, composed by the Icelandic skald. Einarr Skúlason, Sigurðardrápa I (ca. 1110-15?), St. 2 states:
(English Translation): And the mighty king, who got the highest power under {the hall of the sun} [SKY/HEAVEN], nourished his spirit the next winter in Galicia. There I heard that the protector of the people repaid the outstanding earl for his unreliable words; the keen-spirited ruler cheered {the black swan of battle} [RAVEN] (Gade 2009: 539).
Thus, we at least have a near-contemporary account of the occurrence, i.e. the discord between the Norwegian crusaders and the local lord in Galicia.
The author of the poem, Einar Skúlason (ca. 1190-1160?) was an Icelandic clergy as well as poet, and later also composed a Christian poetry Geisli, on St. Olaf of Norway, in 1152/53 (Nordal 2003)
It is not only this Sigurd's expedition that the Scandinavians got into trouble with the local population in NW Iberian Peninsula in later saga traditions, though: In the Saga of the Earls of Orkney (Orkneyinga Saga), Earl Rögnvald Kali of Orkney and other Orcadian and Norwegian chieftains also traveled to the Holy Land by way of Gibraltar, they also dropped in at Galicia to replenish provisions, and they did so by attacking the castle of 'a foreigner who occupied the local castle and harassed the people around it' (Orkneyinga Saga, Chap. 86; ÍF XXXIV: 213). Earl Rögnvald's crusading episode was clearly written under the influence of preceding King Sigurd's, so we are not sure whether this (latter) case also actually happened in course of Rögnvald and co.'s crusade.
These evidences suggest, at a first glance, that the 12th century Scandinavian crusaders did not felt remorse of conscience in plundering the provisions of the local population as their ancestor as the Vikings did in a few centuries before.
It is worth noting, however, that the medieval authors in fact make withholding to describe the skirmish as an one-sided attack from the Scandinavian crusaders if we look closely at the texts: Einar uses the adjectives 'unreliable' (see above) for the word (promise) by the local ruler in Galicia that presupposed the previous breach of contract, and the anonymous author of the Saga of the Earls of Orkney indirectly justify Earl Rögnvald by asserting that the lord of the castle was foreigner and tyrant against the local population. Thus, I think this kind of trouble was not generally no problem, but tolerated under a certain special condition like these ones.
This is almost all what I can comment on this topic from a specialist of medieval Scandinavia. There will probably be more to be explored from a view of medieval Iberian studies, though......
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