First official suggestion of rum used as a weapon against the natives in a 1763 communication from Gladwyn to Jeffrey Amherst while announcing the overtures of peace from Pontiac...

Detroit Nov. 1

"Yesterday, M. Dequindre, a volunteer, arrived with despatches from the Commandant of the iLlionois, copies of which I enclose you....The Indians are pressing for peace....I don't imagine ther will be any danger of their breaking out again, provided some examples are made of our good subjects, the French who set them on....They have lost between 80 and 90 of their best warriors; but if yr Excellency still intends to punish them further for their barbarities, it might easily be done without any expense to the Crown, by permitting a free sale of rum, which will destroy them more effectually than fire and sword."

Source, THE CONSPIRACY OF PONTIAC Francis Parkman