He was the first Wesleyan Methodist in Africa and went to Sierra Leone in Nov 1811.
Warren had been an itinerant preacher travelling through England and Wales for John Wesley's circuits.
[3] Warren volunteered to become a missionary and educationalist in Sierra Leone, and sailed there in 1811 on board the Traveller, captained by Paul Cuffee.
He was accompanied by three school teachers: Jonathan Raynor, John Healey and Thomas Hirst.
He died on 26 July 1812,[3] within 8 months of arriving, a victim of the climate.