S4·E5 Episode 5

THE UNUSED WEAPON: By 1945 the Allies and the Nazis had stockpiled five times more chemical weapons than had been used throughout the First World War. They were never used. Why? Robert Harris reports.

SUICIDE OF A CAVALIER: At the battle of Newbury in 1643, Lord Falkland charged headlong to his death. His friends thought it was suicide. Now a psychiatrist has reopened the case and offers an explanation.

THE FORGOTTEN BRITISH EMPIRE: Who has heard of Carausius? Yet in the third century, he ruled Britain as his separate empire and defied the power of Rome. Timewatch uncovers the few traces of him that remain.