The camp held soldiers from the United States, the United Kingdom, the Netherlands, Australia, and New Zealand. Among the notable prisoners were Brigadier General Thomas J. H. Trapnell, Colonel Edwin H. Johnson, and Sir Mark Aitchison Young, the former Governor of Hong Kong who had surrendered the colony to Japan in December 1941. The diversity of the prisoner population reflected the breadth of Japan's military campaigns across the Pacific. These were men captured in the Philippines, Hong Kong, Singapore, and the Dutch East Indies, transported thousands of miles to a camp in the frozen interior of Manchuria.

Peaty's diary recorded what the camp's medical staff tried to conceal. Prisoners received regular injections that were presented as preventative vaccinations but were in fact inoculations with infectious diseases. His entry for 30 January 1943 notes: "Everyone received a 5 cc Typhoid-paratyphoid A inoculation." The wave of deaths that followed within weeks told the true story. The camp was associated with Unit 731, the Imperial Japanese Army's biological weapons research group, which used prisoners across Manchuria as test subjects for pathogens including plague, cholera, anthrax, and typhus. The men at Hoten Camp were not merely prisoners; they were experimental subjects whose suffering was carefully documented by their captors and secretly documented by one of their own.

Poor conditions, inadequate food, and the absence of proper medical care compounded the effects of the experiments. In a 1981 interview with the Imperial War Museum, Peaty recalled his first impression of the camp: "I was reminded of Dante's Inferno -- abandon hope all ye who enter here." The senior ranking Allied officer in the camp, Peaty bore the burden of maintaining discipline and morale among men who were being systematically weakened and killed. His secret diary, now preserved in the Imperial War Museum's archives, remains one of the most direct firsthand accounts of the atrocities committed at Hoten Camp.

In August 1945, as the Soviet Union declared war on Japan and invaded Manchuria, troops from the 262nd Rifle Division of the 39th Army reached the Hoten Camp. A small team from the American Office of Strategic Services accompanied the Soviet liberators. Of the 1,420 prisoners documented in archival records, 1,193 were liberated. The 224 who had died included victims of disease, malnutrition, exposure to Manchuria's brutal winters, and the medical experiments that Major Peaty had meticulously recorded in his hidden diary. The camp's story was largely overshadowed by the broader revelations about Unit 731 that emerged in the postwar years, but for the families of the men who were held there, Hoten Camp was the specific place where their husbands, fathers, and sons suffered -- not a statistic in a larger horror, but the horror itself.