While Dom Pedro, the Emperor of Brazil, was the king's oldest son, his younger brother Miguel contended that Pedro had forfeited his claim to the throne by declaring Brazilian independence and by declaring war on the Kingdom of Portugal, therefore violating the succession rules mentioned in the Fundamental Laws of the Kingdom.

In the Portuguese Constitutional Charter, Pedro attempted to reconcile traditionalists and liberals by allowing both factions a role in the government.

The traditionalist party of the landowners and the Church, however, were not satisfied with this compromise, and they continued to regard Miguel as the legitimate successor to the throne on the grounds that according to the Portuguese succession rules (approved by the Cortes after the 1640 Restoration), Pedro had lost the right to the Portuguese crown, and therefore to choose a successor, when he took possession of a foreign crown (Brazil).

On May 18, the garrison in Porto, the center of Portuguese progressives, declared its loyalty to Pedro IV and his daughter Maria II, and the Constitutional Charter.

To protect British interests, a naval squadron under Commander William Nugent Glascock in HMS Orestes was stationed in the Douro, where it came under fire from both sides.

The Liberals occupied Portugal's major cities, Lisbon and Porto, where they commanded a sizable following among the middle classes.

Operations against the Miguelites began again in earnest in early 1834, a year marked by the end of Spanish support which had changed sides to the liberals in 1833.

Meanwhile, the Liberal army had suffered a sound defeat at Alcácer do Sal, which proved that, despite the Duke of Terceira's recent march from Faro to Lisbon, the south was still loyal to the Miguelites.

The Miguelist army was still formidable (about 18,000 men), but on May 26, 1834, at Evoramonte, to end the bloodbath in the country after six years of civil war[4] a peace was declared under a concession by which Miguel formally renounced all claims to the throne of Portugal, was guaranteed an annual pension, and was definitively exiled.