Spaniards charge behind their backs with the bad conscience of knowing that their ancestors colonized Latin America more than 500 years ago. But what many still ignore is that, in addition to colonizers, they were also slave-owners.

In the middle of the 19th century, 60% of the "slave" ships crossing the Atlantic were Spanish -mainly from Catalonia and the tiny island of Menorca- who managed to make great fortunes with the slave trade in Africa.

At that time, slavery was already an illegal business in Spain, which would explain the lack of historical evidence (such as commercial receipts or purchase invoices) and thus the difficulties when investigating in the Spanish slavery past. However, historians have been able to demonstrate that the slave trade generated more income than the plantations in Cuba and the exploitation of natural resources in other Latin American colonies. All this money from the slave trade later became a key factor in financing Spanish banking and industrialization in the nineteenth century.

A good example is Antonio Vinent, a Minorcan slave trader, who owned a slave factory in Africa. Vinent went on to make a great fortune captaining slave ships to Cuba and bribing officials to keep his business alive. Vinent became a very popular man: he often organized parties in his Madrid mansion, attended by members of royalty, and was also one of the props of the Banco Hipotecario de España and Banco de Castilla.

"A slave trader is supposed to be a buccaneer or pirate, reckless, arrogant, vulgar. But the slave-owners of Cadiz may be among the most elegant men in Spain, "said an English traveler of the time, quoted in a book by Catalan anthropologist Gustavo Nerin, one of the greatest experts in Spanish colonialism in Africa.

Money from the illegal slave trade became a key factor in financing the Spanish industrialization of the 19th century.

Cadiz, Santander, Barcelona and Mahon (Menorca) were the main ports of origin of the ships loaded with African slaves, managed mainly by rich Catalan and Minorcan families.

 "We have the records of the sea port movements, but not the associated business documents," explains Nerín in an interview with the newspaper Diari Ara published following the publication of his latest book, Traficants d'Ànimes (in Catalan).

For his research on the Spanish slave traders in Africa, Nerin carried out most of his research in British archives, since the English - the first to abolish slavery and to prosecute overseas traffickers - do keep a detailed record of the movements of the slaveowners.

Another well-known Spanish slave trader was Antonio López y López, Marquis of Comillas, and one of the most influential people of the time in Spain. Residing in Barcelona, ​​López y López amassed a large fortune thanks to the slave trade, which helped him to set up the Banco Hispano Colonial, the General Tobacco Company of the Philippines and the Transatlantic Steam Company, among other companies.

"Everyone was aware about illegal slave trade, but it was never repressed, because the survival of Cuba depended on it," writes Nerín.

Unlike Britain, in Spain there was no strong civilian movement against slavery, not even on the part of the press. Slavery was considered "bad", but necessary to keep the plantations profitable.

 "Everyone was aware about illegal slave trade, but it was never repressed, because the survival of Cuba depended on it"

 Many families who became rich by the slave trade later became board members of large banks, railroad companies, shipping companies and mines. Years later, recognizing its linkage with the practice of slavery and the ownership of African slave factories remains a taboo.

It is estimated that between 1514 and 1866 more than 10 million slaves were shipped worldwide, of which 15% died on the voyage. In Africa, illegal slave factories proliferated since 1835, after slavery was abolished in peninsular Spain. Precarious barracks and fortified warehouses served to "store" the slaves until another new ship could be filled for America.

 "It was a large-scale business. It did not work on the basis of kidnappings, but there were commercial networks in which many Africans were involved too. According to Nerín, many slave traders married Africans to maintain contacts with their African dealers.