On 24 August 1820, a liberal revolution occurred, quickly spreading without resistance to the rest of the country. In 1822, a liberal constitution was accepted, partly through the efforts of the liberal assembly of Porto (Junta do Porto). When Miguel I of Portugal took the Portuguese throne in 1828, he rejected this constitution and reigned as an absolutist monarch. A Civil War was then fought from 1828 to 1834 between those supporting Constitutionalism, and those opposed to this change, keen on near-absolutism and led by D. Miguel. Porto rebelled again and had to undergo a siege of eighteen months between 1832 and 1833 by the absolutist army. Porto is also called "Cidade Invicta" (English: Unvanquished City) after successfully resisting the Miguelist siege. After the abdication of King Miguel, the liberal constitution was re-established.