 Colby's preaching was instrumental in the conversions of hundreds of new believers and the formation of many new Free Will Baptist churches in Vermont, Rhode Island and New Hampshire.He was known as a self-sacrificing, humble man who travelled tirelessly from town to town throughout the United States in search of "lost souls".Colby developed consumption and died at the house of William M. Fauquier, Deacon of the Baptist church in Norfolk, Virginia at the age of 29.