Civil Resettlement Units (CRUs) was a scheme created during the Second World War by Royal Army Medical Corps psychiatrists to help British Army servicemen who had been prisoners of war (POWs) to return to civilian life, and to help their families and communities to adjust to having them back. Units were set up across Britain from 1945 and later expanded to provide for Far East Prisoners of War (FEPOWs) as well as those who had been captive in European camps. By March 1947, 19,000 European POWs and 4,500 FEPOWs had attended a unit.

During the First World War and shortly afterwards, many psychiatrists including Sigmund Freud assumed that soldiers who had been captured were 'virtually immune' from psychological harm because they were at a safe distance from battle. This was linked with the belief that shell shock might be a way of escaping from danger. Around the time of the Second World War, this view began to change. Psychiatrists and psychologists such as Millais Culpin and Adolf Vischer argued that POWs were at risk of mental harm, and Vischer coined the term "barbed-wire disease" to describe this condition. Psychiatrists had been keen to look into these ideas, and the outbreak of war gave them the opportunity to conduct research. The 1929 Geneva Convention had changed how POWs were dealt with by setting forth rules for prisoner exchange which made it possible for POWs to be returned to their home nations before the end of the war.

In September 1943, Lieutenant General Sir Alexander Hood hosted an Army meeting at the Directorate of Army Psychiatry to discuss the repatriation of POWs, at which it was decided that British Army psychiatrists should investigate what difficulties POWs might experience on their return home, and how these difficulties might be dealt with. As with much British Army psychiatry during the Second World War, work on rehabilitating POWs was headed by a group who called themselves the "Invisible College" and who formed the Tavistock Institute after the war.

POWs experiencing the most apparently severe difficulties on repatriation were treated at military psychiatric hospitals such as Northfield Military Hospital. Psychiatrists Major Whiles and Alfred Torrie noted that patients were often 'markedly resentful of everyone and everything.' Psychiatrists suggested that these feelings could lead to civil unrest after the war if experienced by the significant number of POWs who would be returning.

Psychiatrist Major Wilfred Bion and psychologist Lieutenant Colonel Eric Trist conducted work at No. 21 War Office Selection Board (WOSB), Selsdon Court Hotel, Surrey where they attempted to adapt officer selection methods to the purpose of selecting POWs who might be capable of returning to active service. The "officer reception unit" was intended to 'provide them with advice on military retraining and re-employment, and on other problems.' Bion suggested that resettlement should use 'psychiatric machinery; but the machinery need not cause irritation by creaking' and so any programme for handling POWs should appear more military than medical though it should incorporate psychiatric treatment in a subtle manner.

At No. 1 RAMC Depot at Boyce Barracks in Crookham, psychiatrist Major A. T. M. "Tommy" Wilson headed an experimental programme to rehabilitate repatriated medical personnel. The experiment ran from November 1943 to February 1944, and involved 1200 POWs undergoing a four-week programme of rehabilitation and training. POW problems included low morale, absenteeism, high levels of sickness, and psychological disturbance. Conclusions from the experiment were published in a memorandum titled The Prisoner of War Comes Home. This document argued that most POWs were not mentally ill but were maladjusted, and required support on their return home.

In February 1944, the War Office agreed to establish a voluntary scheme to help POWs return to Britain based upon the Army psychiatrists' work. This scheme was announced in the House of Lords in July 1944. In November 1944, a pilot unit called No. 10 Special Reception and Training Unit (SRTU) was set up in Derby. Wilson was selected to head this Unit as opposed to Bion, who expressed his dismay in a letter to fellow psychiatrist John Rickman. Bion believed that the psychological principles underpinning the CRUs, which built on his earlier work at Northfield, were underdeveloped and needed further refinement. However, the first group of POWs were imminently due to return to Britain from Germany, which is likely why Wilson was selected to lead the SRTU.

The SRTU pilot indicated to the Army psychiatrists that some changes were required before a scheme could be created on a larger scale. The "hutted camp" was too similar to a stalag, so more luxurious accommodation should be provided in future, and the proposed six weeks was deemed too long and so cut to four weeks. Lectures were not very popular, but visits to workshops proved unexpectedly popular, so the team built connections with the Ministry of Labour to facilitate work placements and visits. Food was a particular concern of POWs, so table service was provided rather than having men queue.