Despite the high-minded ideals of the Declaration of Independence, the American Revolution of 1783 was a bloody business. It brought torture and arbitrary execution to America's cities, tore families apart, and drove 60,000 people into exile. Liberty's Exiles (shortlisted for last year's Samuel Johnson prize) follows the fortunes of those on its losing side  the American loyalists whose allegiance to George III rendered them enemies of the new United States.

They scattered all over the world. Some sought refuge in Britain itself, others in outposts of the British Empire: Canada, the Caribbean, Sierra Leone and India. Jasanoff explores the loyalist diaspora through nimble leaps between historical narrative and individual histories, her characters bringing to life a global story about revolution and displacement. Some, like Thomas Brown, were brutalised by their experiences at the hands of the patriots; others turned to God as they struggled to make sense of their fate. Elizabeth Johnston went to Scotland, then to Jamaica, and eventually to Nova Scotia. She watched her children die, spent long periods apart from her husband, and had her entire life shaped by the political convictions of the men around her. Yet she retained the strength to record her experiences in memoir, including her experience of religious conversion on the journey back from the Caribbean to Britain. Johnston's memoir is one of many personal accounts of loyalist exile on which Jasanoff draws, and her voice echoes through this grand narrative of loss and rediscovery.

The same is true of David George, a former slave from Virginia, one of the thousands of black loyalists who fought on the side of the King in exchange for freedom. George became a Baptist preacher and drew large congregations first in Nova Scotia and subsequently in Freetown, Sierra Leone, where he was one of the early settlers.

Slavery shapes the history of the loyalist diaspora but, Jasanoff argues, was simultaneously transformed by the "spirit of 1783" as the Abolitionist movement in Britain developed in response to defeat in America. Liberty's Exiles articulates the human tragedy of the American Revolution, but it also illustrates its political impact on a resurgent British Empire. It tells an epic story: fittingly so, since it is itself epic in scope, ambition and achievement.