Battle of Dun Nechtain

The Battle of Dun Nechtain, also known as the Battle of Nechtansmere (Old Welsh: Gueith Linn Garan), took place on May 20, 685, between the Picts led by King Bridei Mac Bili and the Northumbrians led by King Ecgfrith. The conflict marked a significant moment in the disintegration of Northumbrian control over northern Britain, which had been established by Ecgfrith's predecessors.

Throughout the 7th century, the Northumbrians extended their influence northward, subjugating several regions, including the Pictish territories. King Oswald's conquest of Edinburgh in 638 and subsequent control over the Picts continued under his successor, Oswiu. Ecgfrith, who became king in 670, faced continuous rebellions, including a notable uprising by the Picts at the Battle of Two Rivers. This rebellion, crushed with the help of Beornhæth, led to the deposition of the Northern Pictish king, Drest mac Donuel, and the rise of Bridei Mac Bili.

By 679, Northumbrian dominance began to wane, with significant setbacks such as the Mercian victory where Ecgfrith's brother Ælfwine was killed. Pictish forces led by Bridei seized the opportunity, attacking key Northumbrian strongholds at Dunnottar and Dundurn. In 681, Bridei also attacked the Orkney Islands, further destabilizing Northumbrian power.

The religious landscape was another point of contention. The Northumbrian church, having aligned with the Roman Church after the Synod of Whitby in 664, established new dioceses, including one at Abercorn. This expansion was likely opposed by Bridei, a supporter of the Iona church.

Ecgfrith's decision to lead his forces against the Picts in 685, despite warnings, culminated in the Battle of Dun Nechtain. The Picts feigned a retreat, luring the Northumbrians into an ambush near what is now believed to be Dunachton, near Loch Insh. The Picts secured a decisive victory, killing Ecgfrith and decimating his army.

This defeat shattered Northumbrian hegemony in northern Britain. The Picts regained their independence, and the Northumbrian diocese of the Picts was abandoned, with Bishop Trumwine fleeing. Although subsequent battles occurred, the Battle of Dun Nechtain marked the end of Northumbrian dominance over the Picts, securing Pictish independence permanently.