The death of King João VI of Portugal in 1826 created a problem of royal succession. The rightful heir to the throne was his eldest son, Pedro I of Brazil, briefly making him Pedro IV of Portugal. Neither the Portuguese nor the Brazilians wanted a unified monarchy; consequently, Pedro abdicated the Portuguese crown in favor of his daughter, Maria da Glória of Portugal, a child of seven, on the condition that when of age she marry his brother, Miguel. In April 1826, as part of the succession settlement, Pedro granted a new constitution to Portugal, known as the Portuguese Constitutional Charter. Pedro returned to Brazil leaving the throne to Maria, with Miguel as regent.
The Constitutional Charter attempted to reconcile absolutists and liberals by allowing both factions a role in government. Unlike the constitution of 1822, this document established four branches of government. The legislature was divided into two chambers. The upper chamber, the Chamber of Peers, was composed of life and hereditary peers and clergy appointed by the king. The lower chamber, the Chamber of Deputies, was composed of 111 deputies elected to four-year terms by the indirect vote of local assemblies, which in turn were elected by persons meeting certain tax-paying and property-owning requirements. Judicial power was exercised by the courts; executive power by the ministers of the government; and moderative power by the king, who held an absolute veto over all legislation.
The absolutists, however, were not satisfied with this compromise, and they continued to regard Miguel as the legitimate successor to the throne because he was Portuguese whereas Pedro was Brazilian. In February 1828, Miguel returned to Portugal to take the oath of allegiance to the charter and assume the regency. He was immediately proclaimed king by his supporters. Although it initially appeared that Miguel would abide by the charter, pressure mounted for a return to absolutism. A month after his return, Miguel dissolved the Chamber of Deputies and the Chamber of Peers and, in May, summoned the traditional cortes of the three estates of the realm to proclaim his accession to absolute power. The Cortes of 1828 assented to Miguel's wish, proclaiming him king as Miguel I of Portugal and nullifying the Constitutional Charter.
This usurpation did not go unchallenged by the liberals. On May 18, the garrison in Porto declared its loyalty to Pedro, Maria da Glória, and the Constitutional Charter. The rebellion against the absolutists spread to other cities. Miguel suppressed these rebellions, and many thousands of liberals were either arrested or fled to Spain and Britain. There followed five years of repression.
In Brazil, meanwhile, relations between Pedro and Brazil's political leaders had become strained. In 1831 Pedro abdicated in favor of his son, Pedro II of Brazil, and sailed for Britain. He organized a military expedition there and then went to the Azores, which were in the hands of the liberals, to set up a government in exile in March 1831. In July 1832, with the backing of liberals in Spain and England an expedition supporting Pedro IV landed near Oporto in 1832 where it was besieged by Miguelite forces. To protect British interests a naval squadron under Commander William Glascock in Orestes was stationed in the Douro where it came under fire from both sides.
In June 1833, the liberals, still encircled at Porto, sent a force commanded by the duke of Terceira to the Algarve and supported by a naval squadron commanded by Charles Napier, alias Calos de Ponza. At the same time, a liberal squadron defeated the absolutists' fleet near Cabo São Vincente. Terceira landed at Faro and marched north through the Alentejo to capture Lisbon on July 24. A stalemate of nine months ensued. The absolutists controlled the rural areas, where they were supported by the aristocracy and the peasantry. The liberals occupied Portugal's major cities, Lisbon and Porto, where they commanded a sizeable following among the middle classes. Finally, the Miguelists lifted their siege of Porto and marched on Lisbon, but they were defeated at Évora-Monte. Peace was declared in May 1834, and Miguel, guaranteed an annual pension, was banished from Portugal, never to return. Pedro restored the Constitutional Charter.