The opulent use of Brazilian gold, the absolutist regime, the movement toward the independence of Brazil, the Methuen Treaty and the Lisbon earthquake contributed to the decline of Portugal's position in Europe and the world.

These events, those at the end of the Aviz dynasty, and the period of the Iberian Union forced Portugal to depend more on its colonies, first India and then Brazil.

The early 18th century, known as the Pombaline Era after Sebastião José de Carvalho e Melo, Marquis of Pombal, was a period of dictatorship and wide-ranging reforms.

He initiated many reforms intended to modernize the country and attacked the power of the privileged nobility and clergy, notably in the case of the Távora affair and the expulsion of the Jesuits.

However, historians also argue that Pombal's "enlightenment," while far-reaching, was primarily a mechanism for enhancing autocracy at the expense of individual liberty and especially an apparatus for crushing opposition, suppressing criticism, and furthering colonial economic exploitation as well as intensifying book censorship and consolidating personal control and profit.

Both monarchs gave excellent positions to Portuguese nobles in the Spanish courts, and Portugal maintained independent laws, currency, and government.

They, together with several associates, killed Secretary of State Miguel de Vasconcelos and imprisoned the king's cousin, the Duchess of Mantua, who had governed Portugal in his name.

John IV also organized the army, establishing the Military Laws of King Sebastian, and developed an intense diplomatic activity that restored good relations with England.

His reign was short due to a conspiracy of his wife, Queen Marie Françoise of Savoy, who joined with Afonso's brother, Prince Peter, to secure an annulment of her marriage to the king in 1667 based on his impotence.

In the same year, Peter managed to gain enough support to force the king to relinquish control of the government and to name him Prince Regent.

An admirer of Louis XIV, John maintained a lavish court paid for by the riches of Brazil and ruled as an absolutist king, ignoring the Cortes (which had only convened sporadically since 1640) and personally appointing ministers.

In the late 17th century, colonial Brazilian explorers known as bandeirantes found gold in what is today the state of Minas Gerais (General Mines).

The world's first great gold rush began with thousands of colonists and slaves pouring into the rugged mountains north of Rio de Janeiro.

The Methuen Treaty cemented allegiances in the War of the Spanish Succession and created favorable trading terms for both nations, especially regarding port wine.

Having lived in two major centers of European enlightenment as his country's ambassador to both Vienna and London, he increasingly identified the Jesuits with their alleged doctrinaire grip on science and education as an inherent drag on an independent, Portuguese style illuminism.

Especially in England, he came in contact with the anti-Jesuit tradition of that country and in Vienna he made friends with Gerhard van Swieten, a staunch adversary of the Austrian Jesuits and their influence.

As prime minister Melo engaged the Jesuits in a dirty propaganda war, which was watched closely by the rest of Europe, and he launched some conspiracy theories about the order's desire for power.

On November 1, 1755, at 9:20 am, a massive earthquake (estimated at 8.5–9.0 on the moment magnitude scale) struck Lisbon, followed by a tsunami and a fire, resulting in the near-total destruction of the city.

After the catastrophe, Joseph developed a fear of living within walls, and the court was accommodated in a huge complex of tents and pavilions in the hills of Ajuda, then on the outskirts of Lisbon.

The King's claustrophobia never waned, and it was only after Joseph's death that his daughter Maria I began building the royal Ajuda Palace, which still stands on the site of the old tented camp.

Contrary to custom and against the wishes of representatives of the Church, many corpses were loaded onto barges and buried at sea beyond the mouth of the River Tagus to prevent disease.

Not long after the initial crisis, the prime minister and the king quickly hired architects and engineers, and less than a year later, Lisbon was already free from debris and undergoing reconstruction.

On April 1, 1758, a brief was obtained from the aged Pope Benedict XIV, appointing the Portuguese Cardinal Saldanha, recommended by Pombal, to investigate allegations against the Jesuits that had been raised in the King of Portugal's name.

The last straw for the Court of Portugal was the attempted assassination of the king on September 3, 1758, of which the Jesuits were alleged to have had prior knowledge (see the Távora affair below).

The events triggered by the attempted murder of King Joseph I in 1758 ended with the public execution of the entire Távora family and its closest relatives in 1759.

Some historians interpret the whole affair as an attempt by the Prime Minister Melo (future Marquis of Pombal) to limit the growing powers of the families of the high nobility.

Sebastião de Melo was made Count of Oeiras for his competent handling of the affair, and later, in 1770, was promoted to Marquis of Pombal, the name he is known by today.

In 1762, France and Spain tried to urge Portugal to join the Bourbon Family Compact by claiming that Great Britain had become too powerful due to its successes in the Seven Years' War.

In spring 1762, Spanish and French troops invaded Portugal from the north as far as the Douro, while a second column sponsored the Siege of Almeida, captured the city, and threatened to advance on Lisbon.

The arrival of a force of British troops helped the Portuguese army commanded by the Count of Lippe by blocking the Franco-Spanish advance and driving them back across the border following the Battle of Valencia de Alcántara.