The Battle of Glen Fruin was a Scottish clan battle fought on 7 February 1603 between the Clan Gregor and its allies on one side, and the Clan Colquhoun and its allies on the other. The Clan Gregor (or MacGregor) and Clan Colquhoun were at feud due to the MacGregors carrying out raids on the Colquhoun's lands. The Colquhouns gained royal support and raised an army against the MacGregors. However, during the subsequent battle of Glen Fruin, the Colquhouns were comprehensively defeated. Glen Fruin is in the Loch Lomond area, in the county of Dunbartonshire, Scotland. In the aftermath of the battle royal policy punished the MacGregors for 150 years.