Update: Since this was first posted, I have researched the family of Mildred Stewart (1775-1820) of Darlington county, South Carolina and I have determined that she was not married to Nathan. Her husband was James Powell (1780-1834). Their children were Sarah b. 1807, Mary Ann b. 1808, Absalom b. 1811, Martha b. 1813, Catherine b. 1815, and Margaret b. 1820. Mildred must have died in childbirth.

For years now, we have taken it for granted that Mildred Stewart (1775-1820) was the first wife of Nathan Fortner. It is said that Mildred Stewart's parents are John Stewart and Susannah Fulkerson. Here's something on the Stewart family that my cousin sent to me.

http://wc.rootsweb.ancestry.com/cgi-bin/igm.cgi?op=GET&db=jamesstewart&id=I00145

This John Stewart was born in Delaware in 1735 and Susannah Fulkerson was the widow of Thomas Bledsoe. John Stewart is such a common name that I believe we may be looking at two different men, both of whom are named John Stewart.
The rootsweb John Stewart is the son of Samuel.

The John Stewart I have is born in 1738 in North Carolina and is the son of James Stewart. Perhaps Susannah Fulkerson is not the correct wife for John Stewart born 1738. Children of John born 1738 in NC are: John, Jr. (1762-1842), James (1763-?), Charles (abt 1770-?), Elizabeth (1765-1859), Robert (abt 1774-Jan 1819), Mildred (1775-1820). It is said that this family moved to Darlington, SC. Mildred is said to have died in Darlington. John, the father, also died in Darlington, SC.

I have found a family in the 1810 Darlington, SC census that seems to be this family.

page 3, John Stewart, Jr.
page 4, Shadrach Stewart
page 5, John Stewart and Robert Stewart
page 7, John Stewart, Sr.
page 8, James Stewart
page 9, Charles Stewart and Silas Stewart
page 10, Elias Stewart
page 14, Adam Stewart

1820 Darlington, SC census
page 4, Charles Stewart, John Stewart, Jr., Elizabeth Stewart, Silas Stewart, Sarah Stewart, John Stewart, Sr.
Since John, Sr. is in the 1820 census, it looks as if we have the wrong date for his death. I think this is more proof that we have confused these two men.

One question I have is: why was Mildred, if she was Nathan's wife, in Darlington with her parents when she died instead of in Edgefield with Nathan and her children. The only thing I can think of is that perhaps she was very sick for a long time and was no longer able to take care of herself or the children so she went home to be taken care of by her parents.

Another question is: in the 1870 census, Amanda Fortner, daughter of Nathan, Jr., is married to John Harrison. John Stewart, age 8, is living with them. Was John a relative of Mildred?

One thing we do know for sure: Margaret Robertson is not the mother of all of Nathan's children. Margaret was born in 1805 in Georgia. She could not have been the mother of Allen, born 1799; Sarah, born 1800; Isaac, born 1801; Avey, born 1802; Ansel, born 1805; Nicey, born 1810; Elizabeth, born 1811; Thomas, born 1812; Mary, born 1815 or Nathan, Jr., born 1817. In 1817, Margaret would have been 12 years old.

As usual, I have more questions than answers. I'm not sure Mildred is Nathan's wife, but then again, I'm not sure she isn't. I will keep things as they are for now until I learn for sure whether this is right or wrong.