The Portuguese empire was the first global colonial empire in history and also one of the longest-lived: it lasted almost six centuries, from the conquest of Ceuta in 1415 to the return of Macau to China in 1999. It all began with a small kingdom of about a million people that learned to sail the open ocean.
Sailing into the unknown
Driven by Prince Henry the Navigator (1394-1460), the Portuguese tackled the problem of navigation in an innovative way when they began the great voyages of exploration along Africa's west coast. Around 1420 the settlement of Madeira, reached a few years earlier, began, and from the 1430s that of the Azores. In this period the Atlantic wind system was studied carefully, and sailors soon realised that they could always get home, whether heading south or west: the prevailing winds changed with latitude and season, and to return from Africa it was enough to swing out in a wide arc into the ocean, the so-called volta do mar. The tool of this adventure was the caravel, a light ship able to sail close to the wind.
The voyages had several aims: to get around the Islamic world to reach Africa's gold and the spices of the East, to find Christian allies, to spread the faith and to satisfy the prince's thirst for knowledge. Tradition has it that Henry founded a school of navigation at Sagres; historians now think rather of a circle of experts gathered around him, where navigation methods and the use of simple astronomical instruments were taught.
Instruments on board
The astronomical instrument first used was the quadrant, a quarter-circle of wood with two sights along one side and a plumb line, which measured the height of a star above the horizon. Officers were told to observe the Pole Star in their port of departure and mark where the line crossed the edge of the instrument. During the voyage the navigator noted the Pole Star's position at rivers, headlands and estuaries, so that the cartographer could work out their latitude and place them correctly on charts. Since the Pole Star does not coincide exactly with the celestial north pole and circles around it, it had to be observed when the Guardas, the two brightest stars of the Little Bear after the Pole Star, were in a set position.
With this system, to reach a place whose Pole Star height was known, the navigator simply sailed north or south until the star reached the desired height and then turned east or west: "latitude sailing". Later sailors were taught to convert degrees into leagues, to know how far they had sailed north-south, multiplying degrees by 16 and two thirds.
In the early 1470s Portuguese ships crossed the Equator, where the Pole Star disappears below the horizon. King John II assembled a commission of mathematicians who around 1485 solved the problem with tables of the Sun's declination, giving the Sun's height at noon on each day of the year and allowing latitude to be calculated. The quadrant, impractical on a rolling deck, was soon joined by the mariner's astrolabe and the cross-staff. The latter, described in the fourteenth century by the Provençal astronomer Levi ben Gershon, spread on Portuguese ships shortly after Vasco da Gama's voyage of 1498, during which he had encountered the kamal, a similar Arab instrument, in the Indian Ocean.
The astrolabe is a calculating as well as a measuring instrument: in its astronomical form it shows the positions of the Sun and the main stars, and knowing the date you can work out their coordinates. The new Portuguese navigation methods spread quickly to Spain and all Western navies.
The route to India
In 1488 Bartolomeu Dias rounded the Cape of Good Hope and ten years later Vasco da Gama reached Calicut, in India. Having struck deals with the great financiers of Antwerp and quickly fitted out one of the most modern fleets of the age, in the early sixteenth century Portugal built, from the coasts of West Africa to those of Asia, an efficient system of ports and fortresses, the Estado da Índia. The country's small population ruled out direct control of vast territories, whose military and administrative management would have been impossible with such limited forces: the effort focused on controlling sea routes and protecting trade. As early as 1500, the year after Vasco da Gama's return, a fleet of thirteen ships led by Pedro Álvares Cabral sailed for India, while the shipyards worked non-stop.
All this led to fierce conflict with those who controlled the old spice trade through the Mediterranean. The Mamluk Sultan of Egypt, harmed as much as Venice, sent a fleet into the Indian Ocean: after an initial Egyptian victory at Chaul in 1508, in 1509 off Diu Francisco de Almeida's Portuguese won a decisive battle for supremacy in the East. Under Afonso de Albuquerque they took Goa (1510), capital of the eastern empire for more than four centuries, and Malacca (1511), key to trade with Indochina, China and the Spice Islands; in 1515 Hormuz, at the entrance to the Persian Gulf, was finally taken. A fortress at Colombo, in Ceylon, secured the cinnamon trade. In 1557 the Portuguese settled in Macau, and for almost a century they were the only Europeans trading with Japan.
Brazil
On his way to India in 1500, Cabral reached the coast of Brazil, which lay within the area assigned to Portugal by the Treaty of Tordesillas. Colonisation began slowly: until the end of the seventeenth century no precious metals were found and emigration remained limited. The Portuguese introduced sugar cane, already tried on Madeira and the Atlantic islands. The indigenous peoples, decimated by European diseases, resisted forced labour, and the labour problem was "solved" by deporting huge numbers of enslaved Africans: Brazil received about 40% of all Africans shipped across the Atlantic. The slave plantation system was later adopted by the French and English in the Caribbean and North America.
Until the early eighteenth century Brazil was a colony of plantations scattered over a vast territory, with few towns. It could not compare with Spanish Mexico or Peru, but that kind of colonisation worked, and with the discovery of gold and diamonds in Minas Gerais in the 1690s, enormous sums flowed to Lisbon during the eighteenth century. Portuguese administration was more rudimentary than Spain's and colonists played a significant role in practice; in trade and taxation, however, Portugal was as unbending as Spain, reserving commerce with the colony to itself, though English merchants had a large share. In 1808 the court itself moved to Rio de Janeiro to escape Napoleon, and in 1822 Brazil became independent.
The African empire and the end
In the nineteenth century, having lost Brazil, Portugal tried to build a new empire in Africa, consolidating control of Angola and Mozambique, as well as Guinea, Cape Verde and São Tomé and Príncipe. In the twentieth century Salazar's dictatorship regarded the colonies as "overseas provinces" inseparable from the mother country: in 1961 India annexed Goa and war broke out in the African colonies, lasting thirteen years. It was the army's weariness with this war that sparked the Carnation Revolution of 1974, after which all the African colonies became independent; in 1975 East Timor was invaded by Indonesia and gained independence only in 2002. With the return of Macau to China on 20 December 1999, the empire came to a definitive end.
The most living legacy of this history is the Portuguese language, spoken today by more than 250 million people in Brazil, Angola, Mozambique and the other countries of the Community of Portuguese Language Countries (CPLP), together with a heritage of architecture, cuisine and mixed cultures across four continents. Alongside it remain the dark chapters of the slave trade and the colonial wars, now the subject of wide debate in Portugal.