By the 1470s Lisbon, Portugal's capital city, became the country's main slave port. The Portuguese slave trade started then not as a trans-Atlantic trade but as an old world trade, supplying slaves to Lisbon and hence onwards to Spain and Italy. In 1539 12,000 slaves were sold in the city's markets. This differed from other European countries' experience of the trade which developed much more in their colonies.

Lisbon also thrived off the businesses associated with slavery, with Portuguese goods exchanged for slaves, goods traded for slaves and goods produced by the slaves. People invested in the trade, and profited, and the Royal family took its share through taxation. African slaves were employed in a variety of occupations but increasingly they were to be found in urban employment such as domestic service.

In 1443 they were able to trade one horse for 25-30 slaves, by 1500 price of slaves rose to match the increased demand, one horse traded for 6 to 8 slaves.

Bases were established on small islands off the West Coast of Africa, the most important being Cape Verde and Sao Thome. These were used for collecting slaves traded from the mainland, who were then sent to Lisbon. The development of sugar cultivation on Sao Thome provided the blueprint for the larger plantation economy of the Americas. The free black and white populations mixed and rapidly and became creolised, which was common to Portuguese colonies.

The Kongo was devastated by its relationship with Portugal. First contact was in 1482 and initially the Kongolese were hopeful that it might be a beneficial relationship based on equality, and there was even an exchange of Ambassadors and the Royal family were baptised into the Catholic Church.

How the Portuguese appear before the King of Kongo Depiction of the meeting between the Portuguese expedition and the Kongolese Royal Family © National Maritime Museum

However over the next few decades the interest shifted towards the slave trade. The King at this time, Alfonso I, despite his efforts to ban the trade, lost half of his kingdom to slavery. In 1611 even the Portuguese King was so concerned at the impact slavery was having he tried to ban whites from the interior, but this was later rescinded.

By the late 15th century Portugal had extended its reach along the East coast of Africa trying to establish a dominance in trade. Their presence was strengthened when during the 1540s some East African Kingdoms ask for help from Portugal in fighting off Ottoman Turkish efforts to expand their empire. Portugal began slave trading in Ethiopia, Mozambique, Magagascar.

However during the 1570s African forces attacked Portuguese colonies in Mozambique and Ghana, a war errupted in Angola, and in 1585 there was a Swahili revolt on E African coast. By the 17th century African revolt and competition from other European powers reduced Portugal's trading to a few coastal outposts.

Major Portugeuse involvement in Brazil began in the second half of the 16th century with sugar as the main export. Plantation methods had already been established in their African island colonies. Success in Brazil increased the need for slaves, and so importation of slaves took off after 1550. This was exacerbated by the discovery of gold in the 1690s, the demand was sustained by the rise in coffee production during the C19th. Throughout this period Brazil imported approx 3.5 million slaves.

© The Atlantic Slave Trade and Slave Life in the Americas: A Visual Record