The immediate purpose of the Proclamation of 1763 was to end Pontiac's Rebellion, a war led by the Indian leader, Pontiac, to protest new British trade and land use policies after the conclusion of the French and Indian War, also in 1763. In the words of the proclamation, King George III said,
[for the] Indians with whom We are connected . . . should not be molested or disturbed . . . no Governor [may] grant Warrants of Survey, or pass Patents for any Lands beyond the Heads or Sources of any of the Rivers which fall into the Atlantic Ocean. . . . We do . . . require that not private Person do presume to make any Purchase from the said Indians of Lands reserved to the said Indians. . . .
Because Pontiac's Rebellion had resulted in the murder of hundreds of American colonists in the Ohio Valley, and the removal of thousands of colonists to the east who were trying to avoid the Indians, the British government's first goal was to assure the Indians under Pontiac's control that their lands would remain theirs, free of any incursion of American colonial settlement. A second goal was to limit American colonial expansion so that Americans would not expand to a territory so large that the British could not reasonably and economically control.
The British ignored, however, the reality of American expansion: colonists had already moved into the new territories gained in the French and Indian War--that is, into the entire Ohio Valley--and Americans assumed that these new territories, west of the Allegheny Mountains, were theirs for the taking. To make matters worse, the Proclamation required American settlers west of the Allegheny Mountains to be removed to the east of the mountains--from the American's perspective, the British gave away to the Indians what the Americans had fought for during the French and Indian War. George Washington, who was interested in land speculation in the Ohio Valley, wrote,
I can never look upon that Proclamation in any other light . . . than as a temporary expedient to quiet . . . the Indians and must fall . . . especially when those Indians are consenting to our Occupying the Lands."
Washington, like many American colonists, assumed that the Proclamation was only a temporary measure designed to stop the hostilities of Pontiac's Rebellion, not a permanent commitment to the Indians that they had sole rights to occupy all new territory west of the Allegheny mountains. His belief that the Indians would consent "to our Occupying the Lands" is a testament to his firm conviction that Indians were not so tied to the land that they would stand in the way of American expansion. As a fairly typical American colonial, Washington saw Indians as a nuisance with no permanent rights to land. Later, during the Revolutionary War, Washington would wage a war of total destruction against Indians who opposed the American effort--wiping out villages, men, women, children and animals to make them move or die.
There were several further breakouts of hostilities with the Indians occupying the new territories even after the Proclamation because several American colonials claimed prior (to the Proclamation) land grants in the new territories, but the essential American reaction to the Proclamation was negative because it cut off a huge area of territory to colonial expansion just at a point when Americans were looking for new territory in which to live.