In 1780, John took ill and had to be brought home by his mother. Thistlewood wrote that John "is very weak indeed & not in his right senses." Doctors of European origin were called and prescribed doses of bark and rhubarb, and, according to Thistlewood, "also laid blisters inside each thigh...They gave him a blister which brought away a great quantity of putrid blood." But despite, or because of, the doctors' attention, John died of a fever on 7 September 1780, though Thistlewood and Phibbah believed that John had been poisoned by a jealous slave.