Linn Duachaill was founded in A.D. 841, the same year as Viking Dublin. The fortress was used as a center by the Vikings to trade goods, organize attacks against inland Irish monasteries, and send captured Irish slaves abroad. For more than 70 years, Linn Duachaill rivaled Dublin as the preeminent Viking holding on the east coast of Ireland before it was eventually abandoned. The discovery of Linn Duachaill will finally allow archeologists to compare the actual site with medieval documents. The names of leaders of the garrison are recorded, along with extensive accounts of attacks they carried out. The site...