It was on April 6th, 1320, that the Scottish nobility, following the Second War of Scottish Independence, issued the Declaration of Arbroath.* This document was forwarded to Pope John XXII in Avignon, France, establishing the historical independence of Scotland and the rights of the Scottish people (read nobility) to choose their own monarch - no matter how vehemently the King of England claimed otherwise.* It is, perhaps, the most important document in Scottish political history, effectively the Scottish "delaration of independence.
Celebrated as Tartan Day.
http://www.tartanday.com/about.htm Germ