In 1816 Maria I, after twenty-four years of insanity, died and the prince regent was proclaimed Joã o VI (r.1816-26). The new king, who had acquired a court and government in Brazil and a following among the Brazilians, did not immediately return to Portugal, and liberals continued to agitate against the monarchy. In May 1817, General Gomes Freire Andrade was arrested on treason charges and hanged, as were eleven alleged accomplices. Beresford, who was still commander in chief of the Portuguese army, was popularly blamed for the harshness of the sentences, which aggravated unrest in the country. The most active center of Portuguese liberalism was Porto, where the Siné drio was situated and quickly gaining adherents. In March 1820, Beresford went to Brazil to persuade the king to return to the throne. His departure allowed the influence of the liberals to grow within the army, which had emerged from the Peninsular Wars as Portugal's strongest institution. On August 24, 1820, regiments in Porto revolted and established a provisional junta that assumed the government of Portugal until a cortes could be convoked to write a constitution. The regency was bypassed because it was unable to cope with Portugal's financial crisis, and Beresford was not allowed to enter the country when he returned from Brazil.

In December 1820, indirect elections were held for a constitutional cortes, which convened in January 1821. The deputies were mostly constitutional monarchists. They elected a regency to replace the provisional junta, abolished seigniorial rights and the Inquisition, and, on September 23, approved a constitution. At the same time, Joã o VI decided to return to Portugal, leaving his son Pedro in Brazil. Upon his arrival in Lisbon, Joã o swore an oath to uphold the new constitution. After his departure from Brazil, Brazilian liberals, inspired by the independence of the United States and the independence struggles in the neighboring Spanish colonies, began to agitate for freedom from Portugal. Brazilian independence was proclaimed on October 12, 1822, with Pedro as constitutional emperor.

The constitution of 1822 installed a constitutional monarchy in Portugal. It declared that sovereignty rested with the nation and established three branches of government in classical liberal fashion. Legislative power was exercised by a directly elected, unicameral Chamber of Deputies executive power was vested in the king and his secretaries of state and judicial power was in the hands of the courts. The king and his secretaries of state had no representation in the chamber and no power to dissolve it.

Two broad divisions emerged in Portuguese society over the issue of the constitution. On the one hand were the liberals who defended it, and on the other, the royalists who favored absolutism. The first reaction to the new liberal regime surfaced in February 1823 in Trá s-os-Montes where the count of Amarante, a leading absolutist, led an insurrection. Later, in May, Amarante once again sounded the call to arms, and an infantry regiment rose at Vila Franca de Xira, 3b8 , just north of Lisbon. Some of the Lisbon garrison joined the absolutists, as did the king's younger brother, Miguel, who had refused to swear to uphold the constitution. After the Vilafrancada, as the uprising is known, Miguel was made generalí ssimo of the army. In April 1824, Miguel led a new revolt--the Abrilada--which sought to restore absolutism. Joã o, supported by Beresford, who had been allowed to return to Portugal, dismissed Miguel from his post as generalí ssimo and exiled him to France. The constitution of 1822 was suspended, and Portugal was governed under Joã o's moderate absolutism until he died in 1826.

Data as of January 1993