During the 15th and 16th centuries Portugal was one of the world's major economic, political and military powers. It had possessions in Africa, Asia, and South America. In 1580 it was united with Spain to form the Iberian Union. However, in 1640 the Portuguese Restoration War led to the re-establishment of the two crowns and empires. Portugal's status as a global power declined following the catastrophic Lisbon earthquake and accompanying tsunami of 1755 that virtually destroyed the capital, and invasions by France and Spain and the loss of its largest overseas possession, Brazil, in the 19th century.

In 1910 Portugal became a republic under a dictatorship. In 1974 following a revolution on the mainland and revolts among its colonies the country adopted a democratic form of government and handed over virtually all its remaining overseas possessions, in particular Angola and Mozambique.