Many POWs were forced not to repatriate.
Inside the camps, anti-communist enclosures used brutal methods to coerce the majority for non-repatriation, "harrowing scenes preceded the official screening, in which violent, systematic terrorism occurred". "Those who wanted repatriation were either beaten or killed". "As a result, when polled the majority were too terrified to say anything but 'Taiwan' repeated over and over again". (MacDonald).
From stories told by POWs who got back to PRC, the KMT agents used most brutal methods to ensure non-repatriation, the details can be found from a book written by a former POW, it is in Chinese and is online. (link to be added)
US did nothing to stop this kind of brutality within the camps, on the contrary , it introduced anti-communists agents into the camps and encouraged their coercions.
From MacDonald:
"In the Chinese camps, the leaders were ex-Guomindong [Kuo-Min-Tang, KMT] soldiers drafted into the PLA after 1949,... this group used 'brutal force' to attain control and force POWs to express their loyalty to the Guomindong. Terror was reinforced by manipulation of essential supplies which were distributed by compound leaders. The choice for the average POW was often to conform or to starve. The situation was tolerated by the camp administration which ... was sympathetic to the anti-communist cause....The Chinese [KMT camp leaders] were in contact with Taiwan through Guomindong personnel in the camp administration".
How did KMT agents get there? From files of the Far East Command, "In January 1951 MacArthur requested 20 linguists from Taiwan who were selected by Jiang's Ministry of Defense. In February 1951 he asked additional 55 and despatched a staff officer to Taiwan to coordinate psychological warfare programmes with Guomindong regime. Muccio recalled that 75 personnel were recruited on Taiwan who were 'doubtless members of the Chang Kai-Shek's Gestapo'."
"After the cease-fire, repatriate POWs were exchanged in OPERATION BIG SWITCH and the non-repatriates turned over to the NNRC [Neutral Nations Repatriation Commission] and the Indian Custodial Force in the DMZ for 'explanations'. The Americans recognised that ...Once outside the UNC control there was no guarantee that large numbers of POWs would not opt for repatriation.... Their main worry was that the prisoners would somehow be separated from the anti-communist leadership which had imposed order in the compounds."
To avert the situation in which many POWs switch to repatriate, US mounted a intensive propaganda campaign with the assistance of the KMT regime, camp leaders held screening to weed any 'communist elements' which remained.
NNRC proposed a rule to segregate POWs who received explanation from those who had not. Americans consider this to be extremely dangerous and objected to it strongly. US news correspondents at Panmunjom warned, "If the Communists succeed in separating anti-Communist leaders from [their] respective compounds, then very appreciable numbers of the prisoners may switch and elect repatriation".
The Americans scored a victory in opposing the NNRC proposal, the anti-Communists elements would appear at the beginning of the explanation and disrupt the proceedings. "Thus the explanations were marked by abuse and violence." "As a result, the mass of POWs was never interviewed. " "Of the Chinese 2085 out of 14700 were screened".
"In a separate report, the Swedes and Swiss agreed that 'The attitude of prisoners of war in respect of explanations has...been influenced and coordinated by organizations of a political nature....acts of violence and even murders have been committed."
So, almost 2/3 of the Chinese POWs were sent to Taiwan.
Upon this victory, US government proclaimed: "They will remember that freedom is the popular choice, and the desire for freedom can overcome even the most intense indoctrination and brutal discipline. We in the free world have a special right to feel proud today. we have stood by a principle and won."
"Western treatment of the Koreans and the Chinese was dictated by a deeply rooted conviction that they were not people like themselves, but near-animals..."( Hastings p307)
Well, let's see what the British say, since they did not guard the POW camps (US did), we can assume that they are more honest on this.
From "The Korean War" by Max Hastings
"Koje-do wasn't managed properly--there were far too many men in one enclosure. There was a lot of bronchitis, pneumonia, dysentery, pinkeye. TB was widespread. There were men with open wounds that were still draining. All of them had lice."
(POW rioted on Feb.18 and March 13, 1952, and UN guards fired into the POWs, killing 89 and wounded 166).
On May 7 1952, the POWs captured the camp commander Brigadier Dodd and tried him for brutality against POWs, and he signed a document that admitted the brutality by US guards, and agreed to cease immediately the "barbarous behaviour, insults, torture...[and] mass murdering" of POWs.
After the Dodd incident, Major D. R. Bancroft reported on Koje-do POW camp situation: "All US troops were apt to regard the PWs as cattle... They...handled them, including cripples who had been badly wounded, extremely roughly". When he questioned the Americans, "Their replay was invariably, 'Well, these people are savages' and on one occasion, 'Congress has never ratified the Geneva Convention anyway'".
In August 1952, British Foreign Office commented on Bancroft's report: "The report confirms other accounts we have had of the 'Hate Asia' attitude so freely displayed by Americans in the Far East. The harm which such behaviour does to our joint cause needs no emphasising."
From "Korea, the war before vietnam" by Callum A. MacDonald
"American medical officers estimated that 50 per cent of the POWs in Pusan were suffering malnutrition in January 1951".
"The POW command instituted a 'shoot to kill' policy. 'POW threw rocks at UNC personnel: POW shot dead', was considered a satisfactory incident report."
"6600 prisoners had died in UN captivity by December 1951".
Contrary to western propaganda of communist brutality, Chinese took the policy of "treating POWs well".
Chinese had the tradition of treating POWs with humanity. 2000 years ago, in its 100 year war (200BC) with the Huns, the government forbid brutality against captives, one Hun captive even became the second highest official in the imperial court, a lot of Huns converted into Chinese. Similar principles were applied in other ancient wars with others. Even after the Sino-Japanese war, China did not use brutality against the Japanese POWs. During the civil war, PLA captured a lot of KMT (Guomingdang) soldiers, and most of them became PLA soldiers and fought against KMT.
From "Korea, the Untold Story of the War" by J. C. Goulden, "...the Chinese showed surprising compassion in their treatment of prisoners, especially the wounded. The Chinese,... in some instances put Americans on litters, carried them to the roadside, and then withdrew and held their fire so that UN medics could remove them."
Let's also quote some text from C. A. MacDonald's book:
-----
The Chinese POW policy (starting quote) "treated POWs as victims of the ruling classes, students who were to be educated and pointed towards the truth. Strict rules were laid down governing the treatment of prisoners. POWs were to be given food and medical treatment. They were to neither robbed nor abused. Instead they were to be led towards an understanding of the true nature of the war and their own societies. After such re-education, prisoners could be either be released at the front to rejoin and demoralise their old units, or held for longer-term indoctrination."
"At the beginning...POWs were given a meal and a political speech, before being released to their own lines. A group of Americans from Almond's X Corps, captured in November, were 'inspected by a Chinese officer who gave them cigarettes, a good meal of chicken, and told them they could rejoin their own forces. Then they were left to their own devices.' Others found themselves greeted by nurses who treated the wounded and distributed gifts of candy...In November/December 1950... Orders [from Pentagon] were issued to evacuate all released POWs through medical channels as quickly as possible."
"Unlike German and Japanese camps of World War Two, these [Chinese POW camps] were relatively open:'There was no barbed wire, no tiger boxes with machine gunes...and only a few guards stationed at strategic points. The Chinese hadn't bothered much about security."
"When repatriation became an issue, POWs were used in another propaganda role. Chinese 'lenient treatment' was contrasted to the brutality of the UN authorities at Koje."
"In February 1953, the [US] State Department noted: 'Defense is particularly concerned lest the Communists release a huge batch of prisoners who...would have to be allowed to go to their widely dispersed home towns, where have been converted, they could do immeasurable harm.'"
"For many returning [American] prisoners, repatriation was to become a 'March to Calumny'".
-----
In MacDonald's book, he implied that Chinese treatment of POWs was 'brainwashing', yes, Chinese were educating the POWs, but the latter had their free mind to discern the truth or falsity in what they heard, what is the problem?
In September 1950, MacArthur issued a directive:"Treatment of POWs shall be directed toward their exploitation for psychological warfare purposes". Indoctrination program were set up in the POWs camps to teach about the evil of communism, and when POWs refused to listen, torture and even murder would befall on them. In the truce talk later, Chinese and North Korean POWs were held hostage by US as the last chance to gain "honor" in the Korean war. Many POWs died in their fight to return home, and many were forced to go elsewhere.