Lord Mansfield gave Judge Henderson the "sanction of his great authority in favor of the purchase." Lord Chancellor Camden and Mr.Yorke had officially advised the King in 1757, in regard to the petition of the East Indian Company, "that in respect to such territories as have been, or shall be acquired by treaty or grant from the Great Mogul, or any of the Indian princes or governments, your Majesty's letters patent are NOT NECESSARY; the property of the soil vesting in the company by the Indian grant subject only to your Majesties right of sovereignty over the settlements, as English settlements, and over the inhabitants, as English subjects, who carry with them your Majesties laws wherever they form colonies, and receive your Majesties protection by virtue of your royal charters." This opinion, with virtually no change, was rendered in regard to the Indian tribes of North America by the same two authorities, certainly as early as 1769; and a true copy, made in London, April 1, 1772, was transmitted to Judge Henderson.

Armed with the legal opinions received from England, Judge Henderson was fully persuaded that there was no legal bar whatsoever to his seeking to acquire by purchase from the Cherokees the vast domain of the trans-Alleghany.

A golden dream of empire, with its promise of an independent republic in the form of a proprietary colony, casts him under the spell of its alluring glamour.
In the meantime, the restless Boone, impatient over the delay in the consummation of Judge Henderson's plans, resolved to establish himself in Kentucky upon his own responsibility.
Heedless of the question of title and the certain hazards incident to invading the territory of hostile savages, Boone designated a rendezvous in Powell's Valley where he and his party of five families were to be met by a band under the leadership of his connections, the Bryans, and another company led by Captain William Russell, a daring pioneer of the Clinch Valley.

A small detachment of Boone's party was fiercely attacked by Shawanoes in Powell's Valley on October 10, 1773, and almost all were killed, including sons of Boone and Russell, and young John and Richard Mendenhall of Guilford County, North Carolina.

As the result of this bloody repulse, Boone's attempt to settle in Kentucky at this time was definitely abandoned.