The Treaty of Westminster (or the Treaty of Westminster-Ardtornish) was signed on 13 February 1462 between Edward IV of England of the House of York and the Scottish John of Islay, Earl of Ross, Lord of the Isles. 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.