Several important dates exist in the Klingon calendar system. These are examined here, along with conjecture on my part about their significance and method of dating.
This is a far more speculative portion of the Klingon calendar examination than the other pages on this topic. There is also quite a bit of information used here that is not gained from novels connected to the Lit-verse. I have included all the information on Klingon holidays I could, regardless of its connectivity with the rest of the literary continuity. None of the speculation here is contrary to anything in the Lit-verse continuity, but it does contain quite a bit of theorizing on my part. If anyone out there wants to offer changes to some of these speculations to make the overall system more coherent, I would love to hear your ideas. And anyone, including any Star Trek authors, are totally free to use any of this for whatever purpose they would like.
The Kenson-Bennett Klingon Calendar begins in 1375. The years of the system are referred to in canon and in the Lit-verse as "the year of Kahless." However, Kahless lived around the 9th or 10th Century according to TNG: "Rightful Heir" and DS9: "The Sword of Kahless." Given the Kenson-Bennett Calendar's assumption that Klingon years roughly correspond to Earth years, this leaves us with the conclusion that Year of Kahless 1 (or 0) cannot be Kahless' birth year, death year, or any other event surrounding his actual life.
However, of note is that in the original unpublished document by Steve Kenson, the Kot'baval Festival, commemorating Kahless's defeat of the tyrant Molor, was the start of the Klingon year, and this event was said to take place in the Year of Kahless 0, and the founding of the First Empire was the Year of Kahless 1.
One important event in Klingon history did occur around the 14th Century: the Hur'q Invasion. According to TLE: The Art of the Impossible, after the defeat of the Hur'q, the Hero Ch'gran constructed a fleet of warships from Hur'q technology and was the first Klingon to venture into the stars. Whether it was this occasion, the defeat of the Hur'q, or some other specific date, it appears the Klingons reckon time from some event in this era of history.
It seems likely that the first system the Klingons would have devoted their effort to visit is Boreth. I speculate that the founding of the Second Empire and the restarting of their calendar at Year of Kahless 1 (Second Empire) occurred on the day that Ch'gran set foot on Boreth and claimed the first new world for the Klingon race. For simplicity's sake, I would say that Ch'gran planned this event to coincide with the start of a new year under the old numbering system, setting foot on Boreth on the Kot'Boval Festival, 1 Jo'vos Year of Kahless 1. On Earth, under the Julian calendar used at the time, this was February 25, 1375. Under the current Gregorian calendar, this would be March 5, 1375.
In the TNG episode "Firstborn", it is said that the Kot'baval Festival is the celebration of the defeat of the tyrant Molor by Kahless in single combat. Traditions observed this day include reenactments of this pivotal moment in Kahless' life. In 2370 this festival took place several days before Stardate 47779.4. That would mean it fell a few days before October 12, 2370 or 27 Maktag 996.
Interestingly, the Kot'baval Festival was also depicted in the Dark Passions duology. This version of the celebration seemed to take place sometime around stardate 47104. This stardate converts to February 8, 2370, or 24 Xan'lahr 995. So the Kot'baval Festival seems to have occurred twice in one Earth year, at approximately six Klingon months apart.
As stated above, in the original document by Steve Kenson, the Kot'baval Festival was the start of the Klingon year, which under my system would be 1 Jo'vos. 1 Jo'vos 996 would add another possible Kot'baval Festival to this period, falling mostly on May 22, 2370
The key to explaining all of this is provided in Prey: The Hall of Heroes, where another Kot'baval Festival is celebrated sometime in April 2386. It is noted that while Kot'boval is usually celebrated on the anniversary of Molor's defeat, it can, as in this case, be celebrated anytime the people's spirits need boosted.
Accepting the original explanation by Steve Kenson, I would speculate that the Kot'baval Festival falls on 1 Jo'vos each year. The leap day of 0 Jo'vos is added to the festival once every five years. So the Kot'baval in TNG: "Firstborn" must have been an irregular date called for by the Empire. And the celebration in Dark Passions likewise must have been a special event called for by the mirror Klingons.
The most widely known holiday of the Klingon year is the Day of Honor. Eight Days of Honor have been depicted onscreen or in the books and comics, and one other has been mentioned. Their timings during the year have never been consistent during any of those usages. Fandom has commonly placed the Day of Honor on March 23rd in the Earth calendar, in honor of the airdate of the first appearance of the Klingons in "Errand of Mercy." However this date does not align with any of the specific dates given for the Days of Honor shown onscreen on in the literature.
TOS: Day of Honor- Treaty's Law
TNG: Day of Honor- Ancient Blood
DS9: Day of Honor- Armageddon Sky
DS9 (Young Adult): Day of Honor- Honor Bound
Marvel DS9 Issue 13: Day of Honor
Star Trek Unlimited comic story: "The Warrior"
VOY: Day of Honor- Her Klingon Soul
Voyager episode: "Day of Honor"
The Klingon Art of War
So we are left with only this concrete information on when Days of Honor occur, which is neither consistent about the time of year, nor the duration between celebrations.
Given the fact that the two Days of Honor B'Elanna commemorates are said to be consecutive celebrations (despite the fact that they occur more than one Klingon year apart, and despite the fact that Worf notes another Day of Honor which takes place between them) I decided to divide the four most specifically dated of the 24th century celebrations into sets of two. A "High Day of Honor" and a "Low Day of Honor." This accounts for B'Elanna only bothering to take note of the "High Day of Honor", while the "Low Day of Honor" celebrations are only mentioned by Worf and Martok, who would be more observant of a lesser cultural occasion.
High Days of Honor
Low Days of Honor
Under this way of looking at things, it becomes interesting that the two Low Days of Honor could be seen as taking place exactly 1.5 years apart. The High Days of Honor don't seem to take place any notable length of time apart. The only Days of Honor which are specifically mentioned as related to the events of Treaty's Law are the Low Days of Honor.
Going with the assertion from the Day of Honor novelization that the two Days of Honor B'Elanna celebrates are consecutive High Days of Honor, and acknowledging the fact that the span of time doesn't seem to be any round length in the Klingon calendar system (certainly not one year), I speculate that the High Day of Honor actually takes place once every Boreth year. This seems to be a logical alternative to once every Klingon year, in the absence of any concrete alternative.
Then to account for the multitude of frequent Days of Honor in the early 2370s, and fitting with the fact that the two Low Days of Honor which we know the time frames of could be said to be spaced 1.5 Klingon years apart, I speculate that the Low Day of Honor takes place twice per Klingon year. I also speculate that the High Day of Honor is an ancient tradition, predating TOS: Treaty's Law, the events of which are commemorated on the Low Day of Honor.
I speculate the approximate period of a Boreth year is 1.5958 Klingon "years." This is exactly 689 Klingon "days," 6 Klingon "hours," 6 Klingon "minutes," 41.75 Klingon "seconds." Despite the discrepancy between the Boreth day and the Klingon day, the Klingons celebrate the High Day of Honor as one full Klingon day. The period between High Days of Honor therefore follows a pattern of advancing 689 days five times out of every eight celebrations, and 690 days three times out of every eight celebrations. The pattern proceeds 689, 689, 690, 689, 689, 690, 689, 690. For reference a pattern begins in Year of Kahless 996.
This makes the High Day of Honor fall on these dates in the 2370s (with the Earth dates the days on which the majority of the Klingon day falls):
The Low Day of Honor being celebrated twice per Klingon year results in the following two dates repeating each Klingon year, based on the date we know from the Deep Space Nine novel. The Earth dates are the days on which the majority of the Klingon day falls in the 2370s.
Given that Worf states the commemoration period for the Low Day of Honor is approximately four Earth days, and he makes a point to say that it falls three days after the first day of the ninth month, I speculate that the holiday is commemorated over the course of four Klingon days, culminating in the actual Day of Honor itself.
I would further speculate that if the High Klingon Day of Honor falls within a Klingon month of a Low Day of Honor, the Low Day of Honor is abrogated.
With this system of arriving at the dates of Days of Honor in mind, we can reexamine the mentions of the Day of Honor we looked at previously, and determine the success of this speculative explanation, and what dates the novels would therefore take place on.
TOS: Day of Honor- Treaty's Law
TNG: Day of Honor- Ancient Blood
DS9: Day of Honor- Armageddon Sky
DS9 (Young Adult): Day of Honor- Honor Bound
Marvel DS9 Issue #13- Day of Honor
Star Trek Unlimited comic story: "The Warrior"
VOY: Day of Honor- Her Klingon Soul
Voyager episode: "Day of Honor"
The Klingon Art of War
As an easy overview, I've calculated the Days of Honor as they would fall under this system for each year from the Next Generation era to the Legacy era. The High Days of Honor are in bold. The underlined date is when the majority of the Klingon day falls, and would be the day on which the Day of Honor would actually be celebrated according to the Earth calendar.
In the audio reference "Conversational Klingon," Empire Union Day is said to take place "in the third month." It honors the uniting of the Klingon people into the First Empire by Kahless the Unforgettable. The third month under my version of the Kenson-Bennett calendar is Lo'Bral.
As we've seen in the examination of the Klingon Defense Force's calendar system, they seem to reckon each year as beginning on 14 Lo'Bral, 109 days after the start of the Kenson-Bennett Klingon year.
I speculate that Empire Union Day takes place each Klingon year on 14 Lo'Bral, and it is this occasion that the Klingon Defense Force is reckoning the start of their year by.
The audio reference "Power Klingon" tells of this Klingon Defense Force commemoration. It celebrates the superiority of the Klingon military. Much eating and drinking are done on this day, especially stuffed to'baj legs. As opposed to the dating given for Empire Union Day, which is said to occur "in the third month," the dating of this holiday is said to be "every tenth Klingon month."
Making note of that distinction in the wording, I take "every tenth Klingon month" to mean that it happens not "in the tenth Klingon month" which would be impossible to reconcile with the Kenson-Bennett Klingon calendar, but rather that it occurs less often than once per year. I have no reasoning for why this takes place as I do with the Day of Honor.
As there has been no specific date for QI'lop ever given, I have no evidence as to when it takes place. Any guess I make would be totally random. So in the face of absolutely no evidence, I will leave the exact date of QI'lop to others to determine.
Kahless' birth date has never been mentioned in canon or the literature. However it is noteworthy that one of the Klingon months is named A'Kahless.
If Kahless was born during the month later known as A'Kahless, that explains why the month seems to be named after him. This is pure speculation on my part, but it seems to make sense.