I did a little more searching for marriage records, but I can't find any. I haven't done any research in Connecticut before, but it looks like they unfortunately do not have a lot of marriage and death records online at FamilySearch or Ancestry. But I'm pretty confident this is the timeline you're looking for:
Ellen Bemis, daughter of Francis and Mary Bemis.
*about 1842-1843 Ellen is born in Connecticut
*about 1863 - marries Horace C. Sickmund (possibly earlier, but not later)
*Feb. 1864 son Horace C. Sickmund is born
*July 1864 Husband Horace Sickmund dies in the Civil War
*About 1865 - Ellen Bemis Sickmund marries Charles Smith (estimated based on estimated birth year of their first child being 1866)