and sought military aid in the Isles from certain king named "", and endured numerous perils together. In fact, Godred's reign in Dublin and the Isles at about this time suggests that he is identical to the Gothrei whom Gruffudd fled to. If Godred was indeed a descendant of Amlaíb Cúarán like Gruffudd, this shared ancestry could well explain the cooperation between the two. On the other hand, although Gothrei is described as Gruffudd's "friend" or "ally", no specific kinship is acclaimed by the source, which may indicate that Gruffudd's appeal was one of mere expediency. Whatever the case, having gained support from the Isles—in the form of an armed naval force of sixty ships—Historia Gruffud vab Kenan records that Gruffudd invaded Anglesey and defeated a force of Anglo-Normans, before the Islesmen returned home. Gruffudd and Gothrei appear to have directed their efforts against the Anglo-Norman castle of Aberlleiniog, before the former tackled other installations. A significant feature of the encroachment of English power into Gwynedd was the erection of a line of mottes along the northern Welsh coast. The strategic placement of these military sites suggests that they were constructed with the command of the sea in mind. As such, this fortified coastal network could have been perceived as a potential threat to Norse-Gaelic mercenarial operations and raiding expeditions in the region, and may partly explain Gothrei's cooperation with Gruffudd. In 1093, at about the time of this cooperation between Gruffudd and Gothrei, the twelfth-century Historia ecclesiastica records the death of Robert de Tilleul, an eminent Anglo-Norman based in Rhuddlan. According to this source, Robert was slain by a certain king named "". Although there is reason to suspect that the latter is identical to Gruffudd, this identification is by no means certain, as the less than impartial Historia Gruffud vab Kenan makes no mention of this episode at all. In fact, another possibility is that the sea-roving Grithfridus is identical to Gothrei, and thus Godred himself. Whatever the case, Historia ecclesiastica states that Robert was slain during a sea-borne predatory raid in which Grithfridus' three-ship force made landfall under the cliffs of Great Orme. The invaders are further said to have ravished the surrounding countryside, loading their ships with livestock and captives. Having crushed Robert's forces, Grithfridus is stated to have had the former's severed head bound as a trophy to the top of his mast. Just as