Answer:
This is what Bing says
"The Royal Proclamation of 1763 was issued by King George III on October 7, 1763. It followed the Treaty of Paris, which formally ended the Seven Years' War and transferred French territory in North America to Great Britain. The Proclamation forbade all settlements west of a line drawn along the Appalachian Mountains, which was delineated as an Indian Reserve. Exclusion from the vast region of Trans-Appalachia created discontent between Britain and colonial land speculators and potential settlers. The proclamation and access to western lands was one of the first significant areas of dispute between Britain and the colonies and would become a contributing factor leading to the American Revolution. The 1763 proclamation line is similar to the Eastern Continental Divide's path running northwards from Georgia to the Pennsylvania–New York border and north-eastwards past the drainage divide on the St. Lawrence Divide from there northwards through New England."
It is true that as a result of the siege of Boston, the British abandoned the city. After eleven months of the siege, the British abandoned Boston and sailed to Nova Scotia.
