Although the ideology of liberalism was known in Portugal in the late 1700s by way of the American and French revolutions, it was not until after the Peninsular Wars that it became a force with which the monarchy had to contend. Freemasonry introduced by foreign merchants played an important role in spreading liberal doctrines in Portugal. In 1801 there were five Masonic temples in Lisbon, and the first Portuguese grand master was elected in 1804. The three French invasions encouraged the spread of liberal ideas. In 1812 Freemasons founded the Sinédrio, a secret society that propagated revolutionary ideas. Radical ideas were also discussed by Portuguese who lived in London or Paris where they had observed and been influenced by the functioning of the British and French systems. Newspapers and pamphlets, despite the vigilance of the crown's censors and police, were smuggled into Portugal and widely read by a small and increasingly important educated elite, called the afrancesados, who wanted to reconstruct Portugal on the French model. After the Peninsular Wars, the exiles themselves returned to Portugal and began to agitate for a constitutional monarchy. One of these was General Gomes Freire Andrade, the grand master of Portuguese Masons, who became the leader of liberals in Portugal. The liberals were eventually to be successful because of a crisis of royal leadership.

Data as of January 1993