In 1941, during the Nazi occupation of France, Cayrol joined the French Resistance, but he was subsequently betrayed, arrested, and sent to the Gusen concentration camp in 1943.
Cayrol thereafter worked at the final inspection of Steyr-Daimler-Puch at KL Gusen I (the "Georgenmuehle" command), where he was able to write literature during breaks.
One of his poems from this era is the text for "Chant d'Espoir", which was set to music by a fellow Gusen I inmate, Remy Gillis, in 1944.
Having escaped death himself, Cayrol was fascinated and inspired by the story of Lazarus who died, whom Jesus returned to life after being dead.
[2] Cayrol founded and edited for ten years (1956–66) the review Ecrire, published by Éditions du Seuil, who had recruited him as an editorial adviser in 1949.