What people remember about Roger Casement is his terrible end. Accused of trying to raise a brigade among Irish prisoners of war with the help of Germany to fight the British in Ireland, he was hanged on 3 August 1916 as a traitor. But the man described by T E Lawrence as having ‘the appeal of a broken archangel’ was for most of his life a compassionate, highly sensitive and courageous social reformer and anti-colonialist. Roland Philipps’s meticulous and sympathetic portrait is not of a man seeking to betray his country but of a patriot and a romantic defeated in the end by treachery. The only small oddity in his fine book is its organisation: Casement’s birth and childhood do not come until page seventy-nine, by which time Philipps has already covered some twenty years of the period Casement spent as an adult in the tropics.

Casement was nineteen, the son of an impecunious Protestant former army officer and a Catholic mother, when he arrived in Boma in the Congo as purser on a steamer. Orphaned at twelve, he had received little education. The mineral-rich Congo was a so-called free state administered by some three thousand Europeans, but in practice it was King Leopold of Belgium’s personal fiefdom, ruled over with exceptional greed and brutality. By the end of the 1880s, Casement was in charge of a Baptist mission station, where he was liked by his fellow workers and loved by the Congolese. Joseph Conrad, who arrived in the Congo to take command of a riverboat, found him companionable and upright. Increasingly outraged by the brutalities he witnessed, Casement wrote furious letters home and eventually produced a fifty-thousand-word attack on Leopold’s savage rule. Conrad called his own Heart of Darkness ‘an awful fudge’ in comparison. Philipps paints a vivid picture of the frenzied Scramble for Africa, and of the adventurers, slavers and ivory hunters who joined the European nations in their rampage for loot.

For a while, Casement served as a customs officer and as a commissioner for the British Foreign Office in what is now Nigeria, and then as consul-general in Brazil, where he collected material on the atrocities practised by the Peruvian Amazon Company against indigenous peoples, no less inhuman than those