Treaty of Westminster (1462)

The agreement proposed that if Scotland was conquered by England, the lands north of the Scottish sea (the Firth of Forth) would be divided between the Lord of the Isles and the Earl of Douglas to be held from the crown of England, while the Earl of Douglas would hold Scotland south of the Firth.

The Scottish crown in the minority of James III of Scotland had taken the Lancastrian side in the Wars of the Roses by welcoming the fugitive Henry VI of England.

Edward IV was forming new alliances with disaffected English and Scottish nobles to reduce the threat posed by the exiled former king, now in the hands of James III's mother Mary of Guelders.

In 1491, in an attempt to get it back, his half-nephew launched the Raid on Ross, which the Scottish king was then able to use as justification for abolishing the powerful Lordship of the Isles itself.

The Douglases were generally, at that time, the heads of the pro-English party in Scotland, pushing for what eventually became a Union of the Crowns and Kingdom of Great Britain.