Afonso VI (Portuguese pronunciation: [ɐˈfõsu]; 21 August 1643 – 12 September 1683), known as "the Victorious" (o Vitorioso), was the second king of Portugal of the House of Braganza from 1656 until his death.^[1] He was initially under the regency of his mother, Luisa de Guzmán, until 1662, when he removed her to a convent and took power with the help of his favourite, the Luís de Vasconcelos e Sousa, 3rd Count of Castelo Melhor.^[2]

Afonso's reign saw the end of the Restoration War (1640–68) and Spain's recognition of Portugal's independence.^[3] He also negotiated a French alliance through his marriage.^[4] In 1668, his brother Pedro II conspired to have him declared incapable of ruling, and took supreme de facto power as regent, although nominally Afonso was still sovereign.^[5] Queen Maria Francisca, Afonso's wife, received an annulment and subsequently married Pedro.^[6] Afonso spent the rest of his life and reign practically a prisoner.^[5][7][8]

Afonso was the second of three sons born to King John IV and Queen Luisa.^[9] At the age of three, he experienced an illness that resulted in paralysis on the right side of his body.^[10][11] The condition was believed to have also affected his intellectual abilities.^[10][12] His father created him 10th Duke of Braganza.^[13]

After the death of his eldest brother Teodósio, Prince of Brazil in 1653, Afonso became the heir apparent to the throne of the kingdom.^[10] He also received the crown-princely title 2nd Prince of Brazil.

He succeeded his father, John IV, in 1656 at the age of thirteen.^[11] His mother, Luisa de Guzmán, was named regent in his father's will.^[11][14]

Luisa's regency continued even after Afonso came of age because he was considered mentally unfit for governing.^[15][16] In addition to lacking intellect, the king exhibited wild and disruptive behavior.^[11][10] In 1662, after Afonso terrorized Lisbon at night alongside his favorites,^[17][18] Luisa and her council responded by banishing some of the king's companions that were associated with the raids.^[18] Angered, Afonso took power with the help of Castelo-Melhor and Luisa's regency came to an end.^[19][20][21] She subsequently retired to a convent,^[22][14] where she died in 1666.^[23]

Afonso appointed Castelo-Melhor as his private secretary (escrivão da puridade).^[24][19] He proved to be a competent minister.^[20] His astute military organization and sensible general appointments resulted in decisive military victories over the Spanish^[25] at Elvas (14 January 1659), Ameixial (8 June 1663) and Montes Claros (17 June 1665),^[26][27] culminating in the final Spanish recognition of sovereignty of Portugal's new ruling dynasty, the House of Braganza,^[28][29] on 13 February 1668 in the Treaty of Lisbon.^[30][31]

Also in 1667, Pedro managed to gain enough support to force Afonso to relinquish control of the government to him,^[38] and he became prince regent in 1668.^[37][6][36] While Pedro never formally usurped the throne, Afonso was king in name only for the rest of his life.^[40][41] For seven years after Peter's coup, Afonso was kept on the island of Terceira^[42] in the Azores.^[29][43] His health broken by this captivity, he was eventually permitted to return to the Portuguese mainland, but he remained powerless and kept under guard. At Sintra he died in 1683.^[42][44][45]

The room where he was imprisoned is preserved at Sintra National Palace.