The Canaries lay around 100 kilometres off the coast of North Africa, and are today a popular tourist destination and province of modern Spain. The islands were colonised by Spain in 1483 and the indigenous Guanche (meaning Men of the White Mountain) were sold into European slavery by French, Portuguese and Spanish traders, and rapidly worn down in Spain's first European sugar plantation, built in Agaete on Gran Canaria in 1484. Spain began investing in African slave labour from the nearby Barbary Coast, and with prisoners captured during the Reconquista, they started a system that would become familiar throughout the Americas and Caribbean.

The location of these islands made them a principal supply base for ships heading across the Atlantic, starting with Columbus's first voyage in 1492. Sugar cane was first carried to the Caribbean and Americas from the Canaries on a return voyage in 1493 to Santo Domingo, and the first shipment cultivated by enslaved Africans was returned to Spain in 1516. Although never a rival to Seville, the merchants and sailors of the Canaries prospered greatly by investing in slavery in the Americas.

Slavery had been part of Spanish society long before their colonisation of the Americas and mostly Africans were legally imported directly after the Spanish (re) conquest. They were known as Ladinos, Africans who had either lived or were born in Spain. Some were prisoners, or descendants of prisoners, captured in the long wars against the Moorish Kingdoms in southern Spain and forced to adopt Christianity. Others had reached Spain over the numerous slave routes that crossed the Sahara desert. Around 10000 ladinos were living in Seville in 1492, and it was quite common to find ladino crewmen working alongside free sailors on the Spanish expeditions of the 15th and 16th centuries, or as 'companions' or 'assistants' to the Conquistadors (the Spanish 'conquerors' of the Aztec and Inca Empires). The Spanish permitted the ladinos certain privileges, including the right to buy their freedom. However, their independent spirit worried the Spanish colonists, who pinned their hopes on the more 'docile' and 'stable' bozales (African born slaves). Legal imports of bozales were sanctioned in 1518, but they proved to be just as determined to resist their oppressors and win back their freedom as the ladinos.

The Italian Cardinal Rodrigo Borgia was selected as Pope in a corrupt election in 1492, taking the title Alexander VI. On May 4th 1493 he issued the 'Inter Caetera' proclamation, which created a line that divided territories in the Americas and Caribbean between the Catholic powers of Spain and Portugal. Everything to the west, which included most of the Americas, was 'handed over' to Spain, and everything to the east, Brazil and all of Africa, to Portugal. While the Pope's order was frequently ignored, it did keep Spain from
any direct involvement in African countries, which paved the way for the Portuguese to become the undisputed middlemen in this chapter of enslavement. Portugal would indeed come to dominate the supply of enslaved Africans for much of the next two centuries. Nevertheless, the Pope backed the calls of Spanish friar Bartholomé de las Casas to protect indigenous Americans from slavery. However his instructions also called for extreme measures against all those who resisted the Spanish and Catholicism. This led to a huge decline in the local population and paved the way towards a higher demand for African labour.

The Casa de Contratación (House of Trade) was set up in Seville in 1503, granting the city the exclusive right to trade with American colonies. These lands were considered the personal property of the Spanish monarchy, and the authorities in Seville were given the job of maximising profits for the royal treasury. All ships bound for the Americas had to leave and return to its docks, and as the undisputed centre of commerce in Spain it became one of Europe's biggest slave ports. The Tobacco Factory, built between 1728 and 1771 was designed to process the crop grown by enslaved Africans in the Spanish Caribbean. The largest industrial complex ever built in Spain by that time, it reflects the huge profits made from the enslavement of African peoples.

In 1713 the Treaty of Utrecht was signed, bringing to an end the War of Spanish Succession (1701-1714), which had involved Britain, France and Spain. As the victor, Britain dictated the peace settlement, and took from Spain a particularly valuable prize. It demanded the Spanish asiento contract, giving it the sole right to provide slaves to all the Spanish colonies for 30 years. The British government sold on the contract to the South Seas Trading Company for the huge sum of £7.5 million, with the promise to transport 144,000 slaves at a rate of 4,800 a year.

Moret was the leading member of the Spanish Abolitionist Society, and as minister for colonial affairs in 1868 he advocated an end to slavery throughout the Spanish Empire. 'The Moret Law', passed in 1870, freed all newborn children from slavery and slaves over 60. It also granted freedom to all those who would help Spain in the Ten Years War in Cuba (1868-78). This also increased the opportunity for the enslaved to buy their freedom. Moret however could not enforce his law in the colonies because he lacked the money to provide slave owners with the compensation they demanded and he faced powerful opposition from all sides.