
In a letter dated 3 November 1813, from Headquarters, Fort George, from General William Henry Harrison to a British General John Vincent, 49th Foot, discussion is made of the use of Native Americans by the British against the Americans, and the treatment of prisoners of war, with the following from Harrison:
“I have never heard a single excuse for the employment of the savage by your Government unless we can credit the story of some British officer having dared to assert that ‘As we employed the Kentuckians, you had a right to make use of the Indians‘.”
Harrison was replying to a message sent by General Henry Proctor, whom he defeated at the Battle of the Thames one month earlier. Proctor’s message, delivered under a flag of truce, asked for Harrison’s return of private property & papers belonging to several British officers that had been captured. Further, Proctor asked for his messenger to be allowed to ‘ascertain the fate of individuals’ (confirm the well-being of captured prisoners) and allow civilians caught in the path of the fighting to be allowed to travel out of its path. In the aftermath of Harrison’s victory at the Thames, Proctor had escaped with the remains of the 41st Foot; he was later relieved and court martialed for his conduct at the battle.

Earlier in his response, which was directed to General Vincent, his new opposite on the Niagara front, Harrison called Proctor’s past conduct concerning indians and prisoners, and thus his standing to make any request on his personal honor, into question:
In making this statement, I wish it, however, to be distinctly understood, that my conduct, with regard to the prisoners and property taken, has been dictated solely by motives of humanity, and not by a belief that it could be claimed upon the score of reciprocity of treatment towards the American prisoner who had fallen into the hands of general Proctor. The unhappy description of persons who have escaped from the tomahawk of the savages in the employment of the British government, who fought under the immediate orders of that officer, have suffered all the indignities and deprivations which human nature is capable of supporting.

Original text:
Official letters of the military and naval officers of the United States, during the war with Great Britain in the years 1812, 13, 14, & 15 : with some additional letters and documents elucidating the history of that period. John Brannan. Washington City; 1823.
Governors Messages and Letters Vol II. Indiana Historical Collections Vol IX. Edited by Logan Esarey. Indiana Historical Commission: Indianapolis; 1922.