Afonso VI was King of Portugal for more than two decades in the 17th Century. He oversaw his country's final independence from Spain, after a protracted war, but found himself powerless for the last part of his reign.

He was born on Aug. 21, 1643, in Ribeira Palace, in Lisbon. His father was the reigning monarch, John IV, and his mother was Luisa de Guzmán. Afonso had a difficult childhood, starting with a severe illness at age 3 that the left side of his body paralyzed. The illness left him with diminished mental capacity. He did learn to read and write but had little appetite for other forms of learning. Afonso had an older brother, Teodósio, who was the heir apparent; however, Teodósio died in 1653, and Afonso became next in line to the throne.

Afonso grew up in a time of war. Spain had seized control of Portugal in 1580, and three Spanish kings named Philip had presided over the Iberian Union for 60 years. In 1640, John joined a number of other nobles in a rebellion, along with members of the clergy and the military, and proclaimed John king. Spain responded by making war, and the two countries fought a number of battles, raids, and skirmishes for more than two decades. John didn't live to see the end of that war because he died in 1656. Afonso, then 13, took over as king. Afonso's mother, Luisa, was regent for six years, until Afonso began to rule in his own right, in 1662. His prime minister was LuÍs de Vasconcelos e Sousa, the Count of Castelo Melhor. Also at that time, Afonso's sister, Catherine, married England's Charles II, further cementing the alliance between England and Portugal.

The latter stage of the war between Portugal and Spain featured a handful of strong victories by Portuguese forces, at Elvas in 1659 and Ameixial in 1663 and Montes Claros in 1665. Spain finally relented on all claims to Portugal, agreeing to the Treaty of Lisbon on Feb. 13, 1668.

Overseas, Portugal won full control of Brazil in 1661, after the Netherlands agreed to give up claims to the northern part of that territory in exchange for full control of Ceylon. As well, Afonso agreed to give control of Bombay and Tangier to England as part of the dowry for his sister's marriage to the English king.

Afonso married Marie Françoise of Nemours. She came not to appreciate Afonso's physical limitations and gained an annulment after just one year of marriage. She then married Afonso's brother, Pedro. That was an exceedingly good for year for Pedro, as he convinced enough of the nobles in the country to support his gaining control of the government. His official title, beginning in 1668, was Prince Regent. However, he was the king in all but name. In fact, Pedro had Afonso sent off as a prisoner to the Azores island of Terceira, where he stayed for several years. In 1672, a number of Afonso's supporters plotted to put him back on the throne and have him marry Maria Anna of Austria, the Queen Mother of Spain and widow of Philip IV; that plot was unsuccessful, but it convinced Pedro to bring his brother back to the mainland and keep him under heavy guard. Afonso died in Sintra on Sept. 12, 1683. Then, Pedro became king in fact.