Many instances of cannibalism by necessity were recorded during World War II. For example, during the 872-day Siege of Leningrad, reports of cannibalism began to appear in the winter of 1941–1942, after all birds, rats and pets were eaten by survivors. Leningrad police even formed a special division to combat cannibalism. Following the Soviet victory at Stalingrad it was found that some German soldiers in the besieged city, cut off from supplies, resorted to cannibalism.
Later, in February 1943, roughly 100,000 German soldiers were taken prisoner of war (POW). Almost all of them were sent to POW camps in Siberia or Central Asia where, due to being chronically underfed by their Soviet captors, many resorted to cannibalism. Fewer than 5,000 of the prisoners taken at Stalingrad survived captivity. The majority, however, died early in their imprisonment due to exposure or sickness brought on by conditions in the surrounded army before the surrender.
The Australian War Crimes Section of the Tokyo tribunal, led by prosecutor William Webb (the future Judge-in-Chief), collected numerous written reports and testimonies that documented Japanese soldiers' acts of cannibalism among their own troops, on enemy dead, and on Allied prisoners of war in many parts of the Greater East Asia Co-Prosperity Sphere.[notes 1]:80 According to historian Yuki Tanaka, "cannibalism was often a systematic activity conducted by whole squads and under the command of officers".
In some cases, flesh was cut from living people. An Indian POW, Lance Naik Hatam Ali (later a citizen of Pakistan), testified that in New Guinea: "the Japanese started selecting prisoners and every day one prisoner was taken out and killed and eaten by the soldiers. I personally saw this happen and about 100 prisoners were eaten at this place by the Japanese. The remainder of us were taken to another spot 50 miles [80 km] away where 10 prisoners died of sickness. At this place, the Japanese again started selecting prisoners to eat. Those selected were taken to a hut where their flesh was cut from their bodies while they were alive and they were thrown into a ditch where they later died."
Another well-documented case occurred in Chichijima in February 1945, when Japanese soldiers killed and consumed five American airmen. This case was investigated in 1947 in a war crimes trial, and of 30 Japanese soldiers prosecuted, five (Maj. Matoba, Gen. Tachibana, Adm. Mori, Capt. Yoshii, and Dr. Teraki) were found guilty and hanged. In his book Flyboys: A True Story of Courage, James Bradley details several instances of cannibalism of World War II Allied prisoners by their Japanese captors. The author claims that this included not only ritual cannibalization of the livers of freshly-killed prisoners, but also the cannibalization-for-sustenance of living prisoners over the course of several days, amputating limbs only as needed to keep the meat fresh.
"Because of the strain involved, scouts were rotated at short intervals. I do not remember the name of the scout who led the second platoon, but it was he who relieved me. Within three minutes after taking the lead, he was hit by a burst from a machine gun. The Japanese had dug in on a coral hill and were waiting for us. We took whatever cover we could find, moved into firing positions, and battled throughout the day and into the night. Daylight came and we put feelers out to see if the Japanese were still there. They had moved out and the scouts body was gone.
We moved up the hill into the evacuated Japanese positions. There, we found him. His body had been carved as though he were a mere piece of beef. All the flesh was gone from his legs, arms, buttocks and chest and his heart and kidneys were missing. We had no doubt that they were eating our dead.
No prisoners, we vowed to ourselves"
This was written by Chester Nycum, paratrooper from 503 PIR on Noemfor.
Full account here: http://corregidor.org/Heritage_Battalion/nycum/ch5.html