535C
William Henry Sedgwick  [Gad Sedgwick / Lydia Unknown]
b. May 13, 1818 Addison, Addison, Vermont
d. bet 1851 - 1860, [Webster County, Missouri]
m. abt 1840, [Tennessee?], Mary C Unknown

Mary C Unknown  [parents unknown]
b. abt 1919, Kentucky
m1 abt 1840, [Tennessee?], William Henry Sedgwick
m2 abt 1860, [Missouri], James M Johnson

Census records:

1850 MO Dallas
Widow Mary
1860 MO Webster

William Henry Sedgwick, youngest son of Gad Sedgwick, disappeared to genealogical researchers for many decades. Those who were descended from him didn't know where he came from; those who knew where he came from didn't know where he went. As late as 1950, after 100 years of genealogy research by George, Frederick, Francis and Hubert Sedgwick, all that was known of him was a that his nephew Samuel Woodford Sedgwick, Jr. had written a letter (to George?) saying that Willliam Henry had "died in Arkansas, leaving a wife and two or three children." Reference to that letter can be found here

However, I have had the good fortune to meet online a few descendants of William Henry Sedgwick, and they have provided a good deal of information. William W Sedgwick, listed below, has sent his family file. It has now been incorporated into the main file for the Robert Sedgwick family group, and the children are listed here.

Children:

Lydia Ann Sedgwick  (535C1)
  b. July 29, 1841, Tennessee
  d. May 27, 1907, Topeka, Shawnee, Kansas
  m. June 14, 1860, Webster County, Missouri, James Johnston
Varney A Sedgwick  (535C2)
  b. 1842, Tennessee
  d. October 22, 1862, Saint Louis, Saint Louis, Missouri
John Gad Sedgwick  (535C3)
  b. September 06, 1843, Benton Twp, Dallas, Missouri
  d. January 29, 1921, Buffalo, Dallas, Missouri
  m. May 17, 1865, Buffalo, Dallas, Missouri, Anna Laura Smyth
William B Sedgwick  (535C4)
  b. 1851, Buffalo, Dallas, Missouri
  d. Bef. March 26, 1875, [Missouri]
  m. August 04, 1867, Dallas County, Missouri, Selah Celia Nichols

Descendants / Researchers:

Willliam Wendell Sedgwick
William H - John G - Wiliam R - Willis W

Mildred Boroff and Carolyn Loughboruogh William H - Lydia Ann - ???