William Allen Hallock [1794-1880] may just be the most influential early 19th century Christian you never heard of. 

Born in Plainfield, Massachusetts, his father, Moses Hallock, was a minister and an educator. Sensing a call to the Christian ministry early on, he attended Williams College, then a hot-bed of revivalist and missionary fervor. From there, he went to Andover Theological Seminary and then received a doctorate at Rutgers College. 

Why was he influential? He founded perhaps the most influential evangelism and discipleship organization of the first half of the 19th century, the American Tract Society [1825]. Historians have described its emergence as having ushered in a "new era in the history of the American churches."

He was its founder, acted as corresponding secretary for many years and personally approved, often edited, and proofed every manuscript the energetic Tract Society released. In his spare time, he also edited The American Messenger and The Child’s Paper.

He also authored Memoir of Harlan Page: The Power of Prayer and Personal Effort for the Souls of Individuals; Light and Love: A Sketch of the Life and Labors of the Reverend Justin Edwards, D. D., the Evangelical Pastor; The Advocate of Temperance, the Sabbath, and the Bible; The Venerable Mayhews and the Aboriginal Indians of Martha's Vineyard; Condensed from Rev. Experience Mayhew’s History Printed in London in 1727, and Brought Down to the Present Century.

Not remembered by many today, he was on the lips of every Evangelical at the time and profoundly impacted American evangelism, access to affordable Bibles, the missionary cause, the abolitionist cause, and more. His life was written by the evangelical biographer of the time, Helen C. Knight, who had also written biographies of Selina Countess of Huntington, the Wesleys, George Whitefield, etc. 

 A fine bifolium dating to January of 1832 having two pages of pre-printed matter and then a full-page handwritten letter by William A. Hallock. 

The printed material, being two full pages, exploring the vast missionary opportunities before the American Tract Society. At just 7 years old as an organization, they had global plans. 

The letter begins with sharing the question the Executive Committee of the ATS had been asking of themselves, "What agency can this Society exert, under the blessing of God, for the conversion of the world?"

He then details what they have accomplished in 7 years; over 550 publications in six languages, with over 20 million copies of their three core works already in circulation; the three being Doddridge's Rise and Progress, Bunyan's Pilgrim's Progress, and Baxter's Call to the Unconverted. 

He then lays out their domestic plan, using agents as missionaries. And for the foreign field, they are eyeing Bombay, Ceylon, the Sandwich Islands, and the Mediterranean; as well as France, Germany, Russia, China, Burma and more. There is then an extensive section on the success of Adoniram Judson in using printed materials to reach the people of India. 

I find no other example of the circular edition of this letter extant, though it later appeared in print in the American Tract Magazine for 1832 and in the Missionary Herald of the same year. 

The manuscript letter, addressed to wealthy Christian philanthropist, Henry Coffin, reads:

"New York 20. January 1832

Mr. Henry Coffin

My Dear Sir,

God in his Providence seems calling loudly on us for immediately & enlarged exertion especially among the Heathen; and we feel constrained to appeal to the friends of Zion for some special effort to supply us with means. May I ask you to give the above sketch of the fields of usefulness now white to the harvest a prayerful perusal, to lay it before your Pastor or other friends and devise some means which you shall judge will most effective (perhaps in some of the ways attended to at the close of the document) to give us such aid as can be soon obtained in Greenfield. We feel that the call is very urgent - that it is for the cause of the Redeemer and the welfar of souls - we pray for such cooperation as you feel will most effectually subserve those great ends. 

$50 L. Dir.
$20 L. Mem. 

Your aff. Bro. in Christ - 
William A. Hallock.
Cor. Sec."

Very good state with tears at folds.