A boko takes a marine lieutenant's head at Morne Bourougue

At first light on 4 April 1920 a patrol of three marines under Second Lieutenant Lawrence Muth climbed the slope of Morne Bourougue near Lascahobas. They saw cacos ahead and opened fire, and the whole hillside answered. Batraville had laid the ambush himself. Two riflemen fought clear carrying a wounded man and left Muth where he had fallen, and cacos dragged him into the bush. A marine patrol under Colonel Little recovered his remains that afternoon. A prisoner described what happened in between. Muth had been shot in the head and the stomach and could not stand, so he was held upright while Batraville made a speech, and Batraville, who was a boko, a ritual specialist, took his head off with a war machete after certain rites. His heart and liver were eaten. A captured general said the brain was smeared on every man's cartridges so their bullets would find marines. Americans called this savagery. Within Vodou the acts had a grammar: an enemy's power passes to whoever consumes it.

By the 1920s more than three hundred thousand residents of the United States were of Caribbean derivation, the accumulated result of migration out of the islands after emancipation. They arrived just as the Great Migration was bringing millions of rural African Americans into northern cities, so the two movements met in the same neighbourhoods and pressed the same demand for inclusion in American society. Marcus Garvey, born in Jamaica in 1887, built the Universal Negro Improvement Association into an organisation that linked struggles for Black equality across the Atlantic. Hubert Harrison, born in the Danish West Indies in 1883, supplied much of the writing that fuelled the Harlem Renaissance of the 1920s and 1930s, alongside the Jamaican American poet Claude McKay. In Martinique at the same period Aime Cesaire was formulating negritude as a literary answer to white racism. The redefinition of Black art in the United States came in large part from people born in the islands.

A commercial and professional class in British West Africa founded the National Congress of British West Africa. It ran branches in the Gold Coast, Nigeria, Sierra Leone and the Gambia. Through the 1920s it extracted the concession of elected African members in the territorial legislatures, most effectively in the coastal towns where this class had matured. The Congress produced offshoots, among them the West African Students' Union, which gave young West Africans in London a place to argue and introduced them to pan-African ideas. Its leaders thought regionally on a practical calculation, since no single colony could face Britain by itself. Many of them held that organising along colonial boundaries made no sense, those boundaries having been drawn by Europeans for European convenience. Nnamdi Azikiwe of Nigeria carried the argument. British officials meanwhile regarded their tropical African possessions as mere geographical units and saw no reason to worry about nationalism in them. Within one generation those units were sovereign states, governed by men who had been students in London.

Dartiguenave held the presidency through the most violent years of the occupation under American military supervision. By 1922 he was protesting the transfer of Haitian money into American banks, and Washington removed him, installing Louis Borno alongside Major General John Russell as high commissioner. The Borno and Russell government ran the country, ignored the violence around it, and denied what it could not ignore. Under Major Smedley Butler the Americans revived the corvée, a labour draft with precedents in French colonial rule and in Henry Christophe's building of the Citadelle. Conscription was indiscriminate. Butler wrote to Franklin Roosevelt, then assistant secretary of the navy, that it would not do to ask too many questions about how the work was done. People walked long routes through the mountains to keep off the roads. The brutality filled the ranks of the Cacos under Charlemagne Péralte and Benoît Batraville, who took their tactics from Dessalines. Fighting between Cacos and Marines killed more than 2,250 Haitians in the first decade, some in combat and some at the hands of careless or predatory Marines.