Princess Isabel Maria, who was ill, as regent. Over the next few months, traditional nobility, clergymen and the vast majority of the population (who were supporters of D. Miguel) proclaimed Miguel King of Portugal. They also annulled the liberal Constitution, persecuted liberals and their supporters, and attempted to obtain international support for their regime. Thousands of liberal idealists were killed, arrested, or forced to flee to Spain, England, the Azores and Brazil. The acclamation was followed by demonstrations in support of absolutism and failed revolutions to reinstate liberalism. The sequence of events inevitably triggered the Liberal Wars between the supporters of absolutism, led by Miguel, and those of liberalism. Miguel tried to obtain international support for his cause, but failed due to British pressure, although the United States and Mexico did recognize his authority. Between 1828 and 1834, forces loyal to progressive liberalism battled the power of Miguel's absolute monarchy. A liberal uprising in Porto led by exiles Pedro de Sousa Holstein (later 1st Duke of Palmela), João Carlos Saldanha de Oliveira Daun (later 1st Duke of Saldanha) and António José Severim de Noronha (later Duke of Terceira), was quickly defeated by Miguel's forces while similar revolts in the Azores and Madeira were similarly defeated (the liberal forces were able to hold onto territory only in Terceira). Portuguese Civil War The political climate began to change in 1830. Popular opposition to Pedro's reign in the aftermath of the dismissal of several of his ministers during a growing economic crisis forced him to abdicate his throne in Brazil in favor of his son, Pedro II, on 7 April 1831. He then returned to Europe, but found little support from England or France for his quest to regain the throne; instead, he collected arms, money and mercenaries to install his daughter on the throne. He then departed for Terceira in the Azores, from where his government-in-exile organized an expeditionary force that disembarked in Mindelo, not far from Porto, on 8 July 1832. With the backing of liberals from Spain and England, and substantial foreign mercenary contingents (who comprised roughly 80% of the liberal forces), Pedro landed near Porto, which the Miguelist forces abandoned without combat. After fighting the inconclusive Battle of Ponte Ferreira, Miguelite forces besieged Porto, engaging in sporadic skirmishes. Throughout the year, most of the battles of the Civil War concentrated around Porto, whose population had whole-heartedly supported the liberal