​​In September 1942, Islanders born in the UK were deported to civilian internment camps in Germany. Over several days, Islanders gathered in ever-increasing numbers to sing patriotic songs in locations overlooking the deportation vessels in the harbour in St Helier. Those being deported also joined in the singing. On 29 September large numbers gathered, and the demonstration got out of control. Flavien Barbier, who was then 33 years old, was arrested as a ringleader and imprisoned.

​In October 1942, Flavien was sentenced initially to three years’ imprisonment for ‘organising a public meeting with anti-German manifestation’, to which two further months were added for ‘concealing stolen goods’, presumably discovered in a search of his home. He was deported to France on 22 January 1943 and sent to Fort d’Hauteville Prison in Dijon before being transferred to Germany in May 1943. He was subsequently sent to Dieburg Prison, which was administered by Rollwald Penal Camp, where his health was severely damaged due to malnutrition and ill-treatment.

​After Rollwald was liberated by American forces in March 1945, despite his weakened state, Flavien became part of the prisoner-run administration of the displaced persons camp and one of its leaders. Although he survived the war, it is clear that Flavien’s experiences in captivity had a profound impact upon his physical and mental health, resulting in long-term institutionalisation in St Saviour’s Hospital and dependence upon alcohol to cope with the flashbacks caused by Post-Traumatic Stress Disorder.​