In November 1807, the royal court of Portugal boarded a fleet under British naval escort and sailed across the Atlantic, leaving the metropolitan homeland as a managed dependency under a foreign general. It was an act of dynastic survival that unravelled an empire.

The Regeneration of 1820 tells the full story of the political earthquake that followed - from the commercial catastrophe of the asymmetric British trade treaties to the secret conspiracy of Porto lawyers who organised the Liberal Revolution; from the Constituent Cortes that drafted one of Europe's most radical constitutions to the counter-revolutionary fury of Queen Carlota Joaquina and Prince Miguel; from the martyrdom of Gomes Freire de Andrade in 1817 to the naval battle at Cape St. Vincent that decided a civil war; and from the Evoramonte Convention that ended the Liberal Wars to the imperfect constitutional order that emerged from a decade of upheaval.

Barrett McMahon traces the human lives behind the constitutional provisions - the merchant families ruined by British imports, the military officers radicalised by years of subordination to a foreign commander, the exiles who built a state in waiting in London and Paris, and the soldiers who held Porto for thirteen months against overwhelming odds.

A narrative history of the moment Portugal became modern, and of the contradictions that made modernity so difficult to sustain.