• William's date of birth was listed as 19 September 1808 in "John Brown's company of 10, report, 1848 June."  His birth and death dates are also confirmed by the inscription on his gravestone. 

Willard Richards Company (1848)

• Age at Departure: 39
• Head of Household

Sources

• Bullock, Thomas, “Deseret Agricultural and Manufacturing Society,” Deseret News [Weekly], 28 Dec. 1859, 341.
• Early Missionary Database
• Find a Grave (Website)
• John Brown's company of 10, report, 1848 June.
• John Zimmerman Brown, comp., Autobiography of Pioneer John Brown, 1820-1896 (Salt Lake City, 1941), 100.
• Journal History of The Church of Jesus Christ of Latter-day Saints, Supplement after 31 December 1848, 18.
• Mississippi company, report, 1848 May.