At his request he was exchanged into service on a slave ship, which took him to the coast of Sierra Leone. He became the servant of a slave trader and was abused. In 1748 he was rescued by a sea captain who had known John's father. John Newton ultimately became captain of his own ship, A Slave Ship, which supplied the slave trade.
Around 1750, John Newton commanded a English Slave Ship. A ship that would make the first leg of its voyage from England, empty until they would anchor off the African coast. Tribal chiefs would deliver to the Europeans men, women, and children captured in raids and wars against other tribes. Ships would also lure Natives to the ships, with trinkets and bright colorful cloth. Africans, at times were capture while hunting, close to their homes. Then the captives would be loaded and, packed for sailing. They were chained below decks to prevent suicides, laid side by side to save space, row after row, one after another, until the ship had as many as 600 Africans, human cargo.
The Spanish Main (Time-Life Books, 1979), p. 63)
Captains sought a fast voyage across the Atlantic's infamous "middle passage," to preserve as much of their human cargo as possible, yet death rates ran 20% or higher, at times. When an outbreak of smallpox or dysentery occurred, the stricken were thrown overboard; or in the case of Amistad were thrown overboard for lack of sufficient food. For those that arrived in the New World, Africans were traded for sugar and molasses ( used to make rum), which the ships would carry to England for the final leg of their voage (triangle trade). Then the cycle would repeat. John Newton transported 12 shiploads, his part of the 6 million African slaves brought to the Americas in the 18th century.
On a voyage home, during a violent storm, a "great deliverance”, according to John occurred. He recorded that when all seemed lost and the ship would sink, he exclaimed, "Lord, have mercy upon us." When the storm was over he reflected on what he had said and believed that God had spoke to him through the storm and that grace began to work for him, he gave his life to Christ. The inhuman aspects of the Slave Trade business began to haunt him, and he left the sea for good.
John Newton wrote a poem, Amazing Grace, that reveals his revelation of that stormy night. The poem is believed to have been set to the tune of his Human cargo. Newton's tombstone reads, "John Newton, Clerk, once
an infidel and libertine, a servant of slaves in Africa, was, by the rich mercy of our Lord and Savior Jesus Christ, preserved, restored, pardoned, and appointed to preach the faith he had long labored to destroy." But his true testimony is in the most inspiring hymn to all People of Color: Amazing
Amazing grace, how sweet the sound
'Twas grace that taught my heart to fear,
Through many dangers, toils and snares,