Why are we speaking English? Replenishing the Earth gives a new answer to that question, uncovering a 'settler revolution' that took place from the early nineteenth century that led to the explosive settlement of the American West and its forgotten twin, the British West, comprising the settler dominions of Canada, Australia, New Zealand, and South Africa. Between 1780 and 1930 the number of English-speakers rocketed from 12 million in 1780 to 200 million, and their wealth and power grew to match. Their secret was not racial, or cultural, or institutional superiority but a resonant intersection of historical changes, including the sudden rise of mass transfer across oceans and mountains, a revolutionary upward shift in attitudes to emigration, the emergence of a settler 'boom mentality', and a late flowering of non-industrial technologies combined with the Industrial Revolution. This book will reshape understandings of American, British, and British dominion histories in the long 19th