When Does "The Kents" #10 (1998) Take Place?
"The Kents" #10 "To the Stars by Hard Ways" Part 2 is a historical fiction comic-book written by John Ostrander that released March 4th, 1998. So when is "The Kents" #9 set?
It takes place on the fictional DC Comics Universe timeline in the year:
We know this because the real-world United States of American Army General George Armstrong Custer appears and he passed on June 25th, 1876 AD. So it must be before June of 1876 AD.

1866 AD - 1868 AD
We know this because the real-world United States of American Army General George Armstrong Custer appears and he passed on June 25th, 1876 AD. So it must be before June of 1876 AD.
More specifically, the previous issue, "The Kents" #9 (1998) ends in July of 1866 AD. So it is probably after July of 1866 AD.
Specifically, a textbox presents us: ‘From the journal of Nathaniel Kent--" August 29, 1866’. So presumably it is August of 1866 AD.
Later, another textbox tells us, "On December 21, 1866, Captain William J. Fetterman led about 80 troopers into an ambush near Fort Phil Kearney and got jumped by Sioux, Cheyenne and Arapaho warriors." This happened in the real world and became known as the Fetterman Fight or the Fetterman Massacre and the date lines up with the real-world event. So it is explicitly December of 1866 AD by this point.
Finally, Nathaniel "Nate" Kent describes an event in which General Custer's command attack a Cheyenne village and kill their leader Black Kettle ("103 Cheyenne were killed, 92 of whom were old men, women and children. Black Kettle was dead."). He and Brian Savage/Scalphunter take part in General Custer's Washita Massacre or the Battle of the Washita River. This also happened in the real-world on November 27th, 1868 AD so it must be November of 1868 AD at the end.
Furthermore, near the end of the issue another excerpt opens 'From the journal of Nathaniel Kent-- "November 13, 1868'.
Additionally, the issue includes a prologue 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.
Finally, there is a flashback to ?.
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" #9.

