Maria I was Queen of Portugal for most of four decades, in the last part of the 18th Century and the first two decades of the 19th Century. She is known for being her country's first queen regnant and also for her struggles with mental illness.

She was born on Dec. 17, 1734, at Ribeira Palace in Lisbon. Her father was the heir apparent, Joseph, and her mother was Mariana Victoria of Spain.

Maria grew up a devout child, spending much time in religious devotions and prayers. She studied religion and theology. Other of her interests were French and Latin. She also liked to ride horses.

Like many other people in Portugal, Maria suffered lasting damage as a result of the 1755 Lisbon earthquake. Like her father, she developed claustrophobia, an aversion to being in enclosed spaces. She welcomed the royal family's move out of the capital city and into a collection of tents in the hills outside the city.

Maria could not be queen if she married a foreign prince. That was the law in Portugal at the time. And as her father's oldest child, Maria was the heir apparent. So in 1760, she married her uncle, Peter, who was her father's younger brother. In all, they had seven children, three of whom lived into adulthood: Joseph (1761), John (1767), and Mariana (1768).

Joseph I died on Feb. 24, 1777, and Maria became Portugal's first ruling queen. Peter, her husband, was named king, but Maria had all of the royal power.

Maria suffered mental maladies. The deaths of her husband (in 1786), oldest son (in 1788), and daughter (in 1788) exacerbated this; and in 1792, she was declared insane. Her surviving son, John, assumed the duties of monarch, while Maria received care from Francis Willis, a doctor who had helped treat Great Britain's King George III.

Portugal, as an ally of Great Britain (which became the United Kingdom in 1800), proved a bastion against the French occupation of Spain during the Napoleonic Wars. British forces reinforced Portuguese positions and joined with Portuguese soldiers in invading Spain during the Peninsular War.

French forces invaded Portugal in 1807, and the royal family fled to Brazil. In 1815, she became the first Brazilian monarch. Maria did not return to Portugal. She died in Brazil on March 20, 1816. Her son, John, named regent in 1799, became King John VI.