The English slave dealers owned the ships, bought the slaves at wholesale, transported the wretches across the sea, and retailed the poor creatures to the planters of the various colonies. Between 1620 and 1770 three million slaves were driven in gangs down to the African seacoast, and transported to the colonies. At this time some of the greatest houses in London, Lisbon and Madrid were founded, and some of the greatest family names were established during these one hundred and fifty years when the slave traffic was most prosperous. De Bau thinks that another 250,000 slaves perished during the voyages across the sea. For the eighteenth century was a century of cruelty as well as gold.