The first recorded raid by the Vikings on Ireland occurred in the 790s and early raids were sporadic and usually took place in the summer. By the 830s the raids became more intense and the Vikings began to erect temporary camps where the raiding parties could over winter. These camps were called longphorts and from these the Vikings could raid inland.
The term ‘longphort’ is taken from Latin for ship and port and was originally used for first Viking settlements in Ireland but later used for various fortifications including those of the Irish. Longphorts were originally constructed to provide a camp for raiding parties. Sites of longphorts were usually at the meeting of a major and minor river and were well defended with ditches. The first recorded longphorts are Dublin and Linn Dúachaill (Annagassan, Co. Louth) which are mentioned in 840. Many of the longphorts were abandoned by the end of the ninth century.
According to Eamonn P. Kelly of the National Museum Athlumney is a possible longphort. When he excavated there in the late 1970s he discovered ditches which may have been aprt of a longphort. He suggested that the site may be Dun Dubchomair. Athlumney is situated on a strategic site near the confluence of the Boyne and Blackwater which would have made it attractive for the Vikings.
During the construction of the railway at Athlumney in the late 1840s human and animal remains were discovered with a copper alloy horse-bit, harness mounts, mounts and “buttons”. These remains were identified as of Viking origin. Human bones, the skull of a horse and seven richly gilt items were also discovered by the workmen in July 1848. The human bones were not buried in any ordered fashion. There was a large quantity of charcoal, extending from 2 to 10 feet below the surface in the surrounding ground.
There was another longphort at Rosnaree. The Annals of the Four Masters refer to a fleet of sixty ships on the Boyne in 836. There is a mention of a Viking site at Linn-Rois in 841 which has been interpreted as the pool of Ross. Conor Brady of Dundalk Institute of Technology has uncovered the possible site of the longphort at Rosnaree. The D shaped enclosure that he excavated dated to the early medieval period.
Another possible Viking longphort is a site at Scurlogstown, Trim, which Rev. William Moran identified as a Viking burial in 1956. Moran writing in Riocht na Midhe suggested that Scurlogstown was the bridgehead for the Vikings and used by them as a base from which to launch an attack on the royal site of Lagore. In 846 Tigearnach, lord of Loch Gabhor (Lagore) gained a victory over the foreigners at Daire-Disirt-Dachonna where twelve score of them were slain by him. In 847 Tigearnach and his allies attacked and plundered Dublin. Moran identified Scurlogstown as a ship burial site. No excavation has taken place at the site.
Duleek monastery was plundered by the Vikings in 830. In 833 Slane was attacked. In 836 Dubh Litir Odhar of Tara was taken prisoner by the foreigners, who afterwards put him to death in his shackles, at their ships. In the same year there were sixty Viking ships on the Boyne in 836. The whole territory was plundered, both churches and habitations of men, and goodly tribes, flocks, and herds. The Irish counter-attacked and one hundred and twenty Vikings were killed by the men of Brega. The Vikings became another factor in the power struggle between warring kings. In 848 the Vikings became the allies of the king of Cianachta Breagh (east Meath) and together their forces attacked Maelseachaliann. The combined army burned Lagore to the ground and plundered the oratory at Trevet. The following year Tigernach and Maelseachlainn drowned the king of Cianachta Beagh in the river Nanny. Also in the year 849 a rival group of Vikings arrived in Ireland and an internal civil war began between the two groups. Sodhomna, the abbot of Slane, was killed by the Norsemen in 854. In 862 Conchobhar, the second lord over Meath, was drowned in a water at Cluain Iraird (Clonard) by Olaf, lord of the foreigners. Flann, king of Knowth was plundered by Olaf in 863. From 873 to 902 Viking activity decreased but sporadic raiding continued throughout the ninth century. In 902 the king of Brega and the king of Leinster attacked Dublin and expelled the Vikings from it for fifteen years.