The Middle Passage was part of the triangular slave-trading route that began in Europe (often Spain or Portugal but also England), went to Africa, and then crossed the Atlantic to the New World. Europeans traded manufactured goods on arrival in Africa, which allowed them to purchase Africans for the slave markets in the New World. When the ships arrived in the New World, the slaves were sold for raw materials, and the ships returned to Europe to begin the cycle again.
Because Africans were considered to be something less than human, they were treated as animals on the Middle Passage, packed tightly into the lower decks and rarely allowed on the main deck for air. Their food was substandard and conditions led to severe diseases such as scurvy and dysentery. Most historians believe that 15% to 20% of the African passengers died on each Middle Passage, and the total number of dead Africans from the Middle Passage is probably 2 to 2.5 million.
Even the crew of ships transporting slaves lived a substandard ship-board life. The companies investing in this trade cared little more for the crew of these ships than they did for the Africans, and many of the crew genuinely disliked the trade. The brutality with which they treated the Africans also had a brutalizing effect on the sailors themselves.
The Middle Passage was so horrific that it became a cultural memory for thousands of African slaves in the New World.