On 6th April 1320 a letter which was signed and sealed by the majority of Scottish nobles left Arbroath for Pope John XXII, at that time based in Avignon, France. Often known as the Declaration of Independence, the original Scottish copy of this document has survived and is now kept in Edinburgh, in the care of the National Archives of Scotland, and is their most treasured possession.

Many see the Declaration as Scotland's first step towards democracy, and it has been used by many as an expression of political independence and has also been linked with the American Declaration of Independence. The 6th April was adopted by the United States of America as Tartan Day, thus giving the date of the signing of the Arbroath Declaration truly international significance.
Info from www.arbroathabbeycampaign.com