When Does "The Kents" #7 (1997) Take Place?
"The Kents" #7 "Brother Versus Brother" Part 3 is a western historical fiction comic-book written by John Ostrander that released December 3rd, 1997. So when is "The Kents" #7 set?
It takes place on the fictional DC Comics Universe timeline in the year:
We know this because William Clarke Quantrill (1837-1865) once again appears so it must be before June of 1865 AD.

1863 AD - 1864 AD
We know this because William Clarke Quantrill (1837-1865) once again appears so it must be before June of 1865 AD.
More specifically, the second page includes a faux-excerpt that begins: 'From the journal of Mary Glenowen-- "September 18, 1863'. So the issue seems to begin in September of 1863 AD.
Then, another reads, 'From the journal of Mary Glenowen-- "December 25, 1863' So it is almost certainly late December of 1863 AD in the middle of the story.
Later, the final letter faux-excerpt begins "March 31, 1864." So it is most likely March of 1864 AD at the end.
Additionally, the issue includes an interlude with Jonathan "Pa" Kent writing to Kal-El/Clark Kent/Superman set in ‘the present’ of the DC Universe. This is unplaceable at this time.
It is a chronologically early comic in the DC Comics Universe multiverse timeline and can be read at its timeline point after the previous issue, "The Kents" #6 (1997).