In 1025, it is stated in the _Annals of Loch Cé_, that a predatory expedition was made by the inhabitants of Fermanagh, on which occasion they burned the crannog on _Loch-n-Uaithne_ (Lough Ooney), “and slew seventeen men on the margin of the lake.” Lough Ooney lies in the county Monaghan, in the barony of Dartry, the chiefs of which territory had their principal residence on this lake, whence they were sometimes designated “Lords of Loch-n-Uaithne.”
In the enumeration of various kinds of fortresses repaired by Brian Borumha, crannogs are included, as recorded in a well-known Irish ms. entitled “The Wars of the Gaedhiel with the Gaill.” In it mention is made of four crannogs, one being near Knockany, county Limerick, and situated in _Lough Cend_, now drained; also the celebrated crannog in _Lough Gur_, in the same county. The site of the crannog of _Loch Saiglend_ has not been identified;[178] the site of _Inis-an-ghaill-duibh_ (_i. e._ the island of the black foreigner or Dane,[179]) is unknown, or at least uncertain; however, in the Dublin copy of the _Annals of Innisfallen_, under date 1016, it is stated to have been situated in the river Shannon. We learn that in some of his numerous conflicts with the Danes, Brian Borumha pillaged various _islands_ in the Shannon, where the invaders had placed their women and children for safety, as well as their treasure, as “there was much gold and other wealth in these islands and fortifications.” In 990 a violent tempest “sunk the island of _Lough Cimbe_ (now Lough Hackett) suddenly, _dreach_ and rampart, _i. e._ thirty feet;” this crannog was afterwards rebuilt by Brian Borumha.
With the Danes, the struggle in Ireland between invaders and invaded was carried on as much in the lakes and rivers as on terra firma. Of the importance attached to crannogs during this contest many instances might be given, but a few will here suffice. In 984 “the islands of Connaught were destroyed by these marauders.” In 933 the crannog of _Lagore_ in Meath was burnt by them; whilst in 848 they fired and dismantled it. Lagore being the residence of one of the principal chiefs of Meath, frequent notices of it appear in the annals, where it is written _Loch-Gabhar_. “_Gabhur_” is an ancient Irish and British word for a horse, and accordingly the name _Loch-gabhra_, which occurs in the life of St. Aidus, is translated _Stagnum-equi_, the lake of the horse,[180] now euphonized “Lagore.” In 967 Beollán, “king” of this place, died; in 907 Maelogra, also “king” of Lagore, was slain; whilst in 868 the son of Edirscel, “king” of Lagore, fell fighting against the Danes. In 865 Tighernach, “king” of Lagore and “half-king” of Meath, died; and in 856 Cinaedh, chief of the present baronies of Upper and Lower Duleek, in Meath, in alliance with the Danes, “spoiled the islands” of Lagore. This entry is of great importance, as it points to the probability of the site of another crannog or crannogs in close proximity to the celebrated historical stronghold dug out of its peaty covering in 1847, and which as early as A.D. 673, must have been of importance, for in that year a considerable battle took place on the shores of the lake. In 927 and 928 the Danes plundered “the islands of Lough Neagh,” and in 922 the same fate befel “the islands of Lough Rea.”