Linn Duachaill (Irish pronunciation: [ˌl̠ʲiːn̠ʲ ˈd̪ˠuəxəl̠ʲ]; "Duachall's pool") is the name of a Viking longphort near the village of Annagassan, County Louth, Ireland.
It has been argued that possibly because of changing tidal patterns, it lacked continuous access to the sea.
"[3] This Turgesius was a colourful figure: he apparently brought the north of Ireland under his rule and enthroned his wife on the high altar of the cathedral at the monastery of Clonmacnoise, but was taken prisoner in 843 by Máel Sechnaill mac Máele Ruanaid and drowned in Loch Nar.
[4] The archeological site of Linn Duachaill was discovered in 2010 on a flat area on the River Glyde, after a team of archeologists and a geophysicist had searched from 2005 to 2007 and found a pattern of straight ditches, unlike the usually circular forts built by the native population.
The team, headed by archeologist Mark Clinton, excavated a "defensive rampart, consisting of a deep ditch and a bank.