'Marxists are retards': Recently unearthed documents reveal that Franco's psychiatrist carried out bizarre experiments on members of the International Brigade in 1930s Spain. His aim: to prove that leftwingers are mad. Giles Tremlett reports.

(From The Guardian)

For dictator General Francisco Franco's chief psychiatrist, Dr Antonio Vallejo Nagera, it must have seemed obvious. If the generalissimo and his fellow right-wing rebels in the Spanish civil war were crusaders for justice, God and the truth, then their leftwing opponents had to be mad, psy-chotic or at least congenitally subnormal.

At the end of the 1930s, Vallejo decided to prove exactly that. The solution, he decided, lay in an abandoned monastery at San Pedro de Cardena, near Burgos, which had become a makeshift jail for captured volunteers from the pro-republican International Brigades.

It was here, in 1938, that International Brigade members were subjected to a bizarre set of physical and psychological tests in one of the first systematic attempts to put psychiatry to the service of ideology. Sixty-four years later, the results of Vallejo's project to unravel the "biopsyche of Marxist fanaticism" have finally come to light.

Former prisoners at San Pedro de Cardena remember being subjected to up to 200 …