Eventually, he was released from the military and joined the crew of an Africa-bound slave ship. After a series of disagreements with the crew of the ship, he was left in Africa where he was enslaved to a slave-trader who brutally mistreated him. Eventually, he was rescued by a sea captain who had been asked by Newton's father to search for him. Later in life, he became the captain of a ship, and when the ship was about to sink in the midst of a great storm, he called out to God. After calling out to God, it seems that the cargo of the ship plugged a hole in the hull, so the ship stopped filling up with water and drifted to safety. As he sailed home to Britain over the next few months, he devoted his time to reading the Bible. By the time he had reached home, he had given his allegiance and trust to Christ.
Newton later became an Anglican minister, and in addition to writing a number of hymns, he worked to abolish slavery, and he served as a mentor to William Wilberforce. Newton died shortly after Wilberforce had succeeded in his campaign to abolish the slave-trade in England, which is an amazing story itself.
To read more about John Newton, I'd recommend either Newton's own autobiography, entitled Out of the Depths, or Jonathan Aitken's new biography, John Newton: From Disgrace to Amazing Grace. Also of interest to some may be William Wilberforce's biography by Eric Metaxas, Amazing Grace: William Wilberforce and the Heroic Campaign to End Slavery or the movie chronicling this story, Amazing Grace.
One of my favorite of John Newton's lesser-known hymns is "I Asked the Lord, That I Might Grow." It is below. Enjoy!
I asked the Lord, that I might grow
In faith, and love, and every grace;
Might more of His salvation know,
And seek more earnestly His face.
’Twas He who taught me thus to pray,
And He, I trust, has answered prayer!
But it has been in such a way,
As almost drove me to despair.
I hoped that in some favoured hour
At once He'd answer my request,
And by His love's constraining power
Subdue my sins, and give me rest.
Instead of this, He made me feel
The hidden evils of my heart;
And let the angry powers of hell
Assault my soul in every part.
Yea more, with His own hand He seemed
Intent to aggravate my woe;
Crossed all the fair designs I schemed,
Blasted my gourds, and laid me low.
"Lord, why is this?" I trembling cried,
"Wilt thou pursue Thy worm to death?"
"'Tis in this way," the Lord replied,
"I answer prayer for grace and faith.
These inward trials I employ
From self and pride to set thee free;
And break thy schemes of earthly joy,
That thou may'st seek thy all in me."