I think the widow of Richard Montgall, i.e. Mary Brittian, married Henry Montgomery on 4 January 1801 at Washington County, Virginia. Still trying to find more information.
Citing this Record
"Virginia, Marriages, 1785-1940," index, FamilySearch (https://familysearch.org/pal:/MM9.1.1/XRDR-VLZ : accessed 30 Jan 2014), Henry Montgomery and Mary Muntgall, 04 Jan 1801.
https://www.genealogy.com/forum/surnames/topics/montgall/32/