The Sword of Kahless, one of the most important artifacts of Klingon history.

Like its people, the history of the Klingon Empire is violent but colorful.

Early History

In ancient times, notably during the early part of the Zanxthkolt Dynasty, Klingons practiced mummification. (Star Trek IV: The Voyage Home)

A painting of Kahless on Boreth

Around the year 900 AD, Qo'noS was ruled by Molor, a tyrannical ruler who was generally unpopular among the people. Kahless the Unforgettable emerged as a champion of the people, and slew Molor in single combat using the first bat'leth, the Sword of Kahless, in the Battle of Qam-Chee. Here, Kahless and the Lady Lukara fought a pitched battle in the city's Great Hall against the soldiers of Molor. While the rest of the city's garrison fled before the 500 soldiers, Kahless and Lukara stood their ground and defeated the forces. Shortly after their victory the two began, what would become known as the greatest romance in Klingon history. (DS9: "Looking for par'Mach in All the Wrong Places") Kahless ruled together with his new wife as Emperor of Qo'noS, despite the fact that he was not of noble birth. Moreover, the defeat of Molor continues to be celebrated in the Empire in the Kot'baval Festival. (TNG: "Firstborn", DS9: "Tacking Into the Wind")

In DS9: "Looking for par'Mach in All the Wrong Places" taking place in 2373, Worf enthusiastically mentions the events in Qam-Chee to have happened "a thousand years ago". However, this would state somewhat of a contradiction as TNG: "Rightful Heir" and TNG: "Firstborn" both state, that Kahless lived 500 years earlier. Either Worf "rounded" the number of years in his enthusiasm, or Kahless and Molor were at least 500 years old, which would be an unrealistic figure, even for Klingons.

Kahless was not just a warrior, but also a philosopher. During his rule, he established a strict warrior code that was adopted into Klingon culture and tradition. His words are frequently invoked by warriors about to enter battle. Among his sayings are, "A leader is judged not by the length of his reign but by the decisions he makes." (DS9: "Tacking Into the Wind") Kahless' legends were recorded in a series of scrolls called the paq'batlh. (VOY: "Barge of the Dead")

According to the non-canon Star Trek: Star Charts, the Klingons first achieved warp capability in the Earth year 930 AD, some six hundred years after the Vulcans.

Over the next 1,300 years, the Klingon Empire slowly expanded, despite a devastating conquest and sack by the Hur'q in the 13th century. The Hur'q were a powerful race from the Gamma Quadrant possibly using the Bajoran wormhole to reach Qo'noS. Although they did not stay long, either because of their nomadic way of life or because of fierce resistance from the Klingons, they did not leave before taking many valuable cultural treasures, including the revered Sword of Kahless. (DS9: "The Sword of Kahless")

In the beginning of the 16th century, the Second Dynasty ruled over the Klingon Empire, but was ended with General K'Trelan assassinating Emperor Reclaw then later putting to death all the members of the Imperial Family. During the next ten years, the Empire was ruled by a council elected by the people, which is referred to as "The Dark Time" by Klingon historians. Following this period a new group of Klingons, called the Third Dynasty, were given the titles and names of the original Imperial Family in order to create the illusion of an unbroken line since the true Imperial bloodlines were cut at the end of the Second Dynasty. (DS9: "You Are Cordially Invited")

During the Second Empire, Chancellor Mow'ga sent a fleet to conquer the Breen, but it was never heard from again. (DS9: "'Til Death Do Us Part")


The Klingon capital on Qo'noS in 2151

By the 22nd century, the Klingons were a major regional power, holding several dozen star systems and fielding a formidable military, the Klingon Defense Force. (Star Trek: Enterprise)

Early Contact with Humans

In the late 2140s and early 2150s, the Klingons were engaged in a fierce internal struggle that, while not amounting to actual civil war, threatened to become a more intense conflict. Numerous attacks had taken place throughout the empire that were blamed on various Klingon factions; it was not realized at the time that the attacks had actually been launched by the Suliban Cabal, who were taking orders from a mysterious individual who was an operative in the Temporal Cold War.

Klaang provides the Klingon High Council with proof that the Suliban Cabal was behind attacks against the Empire in 2151.

Although the Klingons had had occasional contact with the Vulcans prior to 2151, they had not met Humans until a courier named Klaang crashed on Earth while pursued by two Suliban soldiers. After dispatching his two pursuers, Klaang was shot by a local farmer named Moore. Although Vulcan ambassador Soval advised that Starfleet authorities withhold medical treatment and allow Klaang to die, Captain Jonathan Archer intervened and insisted on returning Klaang to Qo'noS aboard his ship, the Enterprise (NX-01).

Archer, however, did not understand the complexity or importance of Klingon tradition, and did not realize that returning Klaang to Qo'noS was a grave dishonor and insult. However, Klaang carried with him proof that the attacks were in fact launched by the Suliban, which averted a civil war. For this service, Archer and his ship were allowed to leave peacefully. However, the incident did not leave Klingons kindly disposed towards Humans. (ENT: "Broken Bow")

By 2153, the Klingon society, including its judicial system, was dominated by the Warrior caste and honor only had a superficial meaning during trials.

In early 2153, the Empire again encountered the Enterprise when the Human ship rescued a refugee ship from Raatooras that was attempting to flee Klingon territory. Captain Archer chose to render assistance to the refugees, but failed to realize the ramifications of his actions, particularly the embarrassment he would cause the Klingons. When the Klingons demanded that the refugees be handed over for trial, Archer refused to comply. Captain Duras of the IKS Bortas intercepted the Enterprise and attacked it, unsuccessfully. Archer was later captured and brought to trial on Narendra III, a Klingon colony, for being an "enemy of the state." In an incendiary tribunal, Archer's "interference" with Klingon affairs earned him a life sentence to Rura Penthe. However, Archer managed to quickly escape from the prison, further embarrassing the Klingons. (ENT: "Judgment")

The Klingons launched several further attempts to recapture Archer, including hiring bounty hunters (ENT: "Bounty") and sending Duras himself to track the Enterprise and recapture Archer. However, Duras was unsuccessful in three different attacks against the Enterprise, and he was finally killed when the Enterprise destroyed his ship during the third attack on the edges of the Delphic Expanse. (ENT: "The Expanse")

Augment Crisis


On its way to apprehend the rogue Human Augments in 2154, Enterprise disables a D5 class battlecruiser.

The Klingon Empire nearly went to war with Earth during the Augment Crisis in May 2154, when a group of Humans hijacked a Bird-of-Prey and ejected its crew into space. Planning to devastate humanity, the Augments tried to escalate the incident by annihilating the Klingon Qu'Vat colony with a biogenic weapon. Fortunately, war was averted when Enterprise destroyed the rogue Humans responsible and saved the colony. (ENT: "Borderland", "The Augments")

A short time later, the Klingons found genetic material of the Human Augments within the wreckage of the hijacked Bird-of-Prey. Fearing that Starfleet may be attempting to create genetically-superior Humans to take over the Empire, they tried to adapt this genetic engineering to improve themselves. An unanticipated side effect was that the Augment DNA caused the Klingon cranial ridges to dissolve. The test subjects did gain increased strength and intelligence, but then their neural pathways started to degrade and they died in agony. One of the subjects was suffering from the Levodian flu, which was modified by the Augment genes to become a deadly, airborne plague that spread rampantly within the Empire posing its gravest threat since the Hur'q invasion. In the first stage of this plague, a Klingon's physiology mutated to become more Human, for which the degeneration of the cranial ridges was a symptom.

A Klingon suffering from the Klingon augment virus in 2154.

With the help of a Klingon scientist named Antaak, Dr. Phlox of the Enterprise was able to formulate a cure that halted the genetic effects of the virus in the first stage, retaining the changes in appearance along with some minor neural re-ordering, but with no development of stage two characteristics, such as enhanced strength, speed, or endurance. This left millions of Klingons, mostly in the warrior caste, without their ridges. As these alterations were even passed on to their children, Phlox and Antaak theorized, that surgical cranial reconstruction might become quite popular for Klingons, who want to restore their outer appearance. Nevertheless, this whole incident embarrassed the Klingons even further and the Empire no doubt began to feel much more contempt for Humans, who were responsible for creating the genetic material in the first place. (ENT: "Affliction", "Divergence")

There is no way to tell when a final cure for the Augment virus was found, or if it was found at all. Any Klingon shown originally without cranial ridges in TOS and then with them in subsequent time periods (e.g. Kang, Koloth and Kor), might simply have undergone surgical cranial reconstruction. Other differences in attitude and methodology between the TOS and non-TOS Klingons can perhaps be attributed to the neural re-ordering caused by the virus.

Cold war

By 2223, relations had degraded to a point where the Klingon Empire and the Federation were constantly on the verge of war. (Star Trek VI: The Undiscovered Country; ENT: "In a Mirror, Darkly, Part II")

Based on conjecture derived from dialogs in Star Trek VI: The Undiscovered Country, TNG: "First Contact" and a deleted line from TOS: "Day of the Dove", it was originally believed that first contact between the Federation and the Klingon Empire took place in the 2220s, and immediately led to the state of cold war that lasted until 2293. However, Star Trek: Enterprise revises these theories, placing the first contact in 2151. Furthermore, in TOS: "The Trouble with Tribbles", Spock states that the dispute over the area around Sherman's Planet began immediately after First Contact with the Klingons, meaning that the political status of this region of space must have been unclear since the 2150s.

The Federation was quickly expanding, and its territory began to approach that of the Empire. Disputes over ownership of various star systems arose, particularly over worlds such as Donatu V, Sherman's Planet, the Archanis sector, and Organia. Although numerous skirmishes were fought between the Federation Starfleet and Klingon forces during this time, both sides refrained from committing to open warfare.

Kor, commander of the Klingon forces occupying Organia in 2267.

However, in 2267 negotiations between the two sides broke down, and the Federation officially declared war against the Empire. The Klingons launched an immediate offensive, seizing several planets including the strategically important Organia. Unexpectedly, the Klingon-Federation War was brought to a sudden conclusion just days after it had begun when the Organians, a race of massively powerful noncorporeal beings, intervened and forced both sides to end hostilities. The Treaty of Organia was then imposed, establishing a neutral zone separating the two powers and instituting a procedure, to be overseen by the Organians, through which planets along the border could be claimed and settled by both sides. (TOS: "Errand of Mercy", "The Trouble with Tribbles")

A number of skirmishes and hostile encounters between the two sides occurred over the next decade, including encounters at Capella IV, Neural, Elas and Beta XII-A. In most of these confrontations, the Klingons tried to gain strategic advantage and secure mining rights for valuable minerals, such as dilithium. (TOS: "Friday's Child", "A Private Little War", "Elaan of Troyius", "Day of the Dove")

A product of the short-lived Romulan-Klingon Alliance: A D7 class battle cruiser, which states an originally Klingon design, equipped with Romulan cloaking technology.

In 2268, the Klingons entered into a brief and ill-advised alliance with their long-time blood enemies, the Romulans. This alliance included a technological exchange, in which the Klingons received cloaking technology in trade for D7-class battle cruisers. (TOS: "The Enterprise Incident") The alliance came to a quick and violent end with the Battle of Klach D'Kel Brakt in 2272. (DS9: "Blood Oath")

The terms of the treaty are partially speculation, but based on the fact that the Klingons were using cloaking devices and ships called Birds-of-Prey in Star Trek III. The significance of Klach D'Kel Brakt is in part speculation, but based on the timing (a century before the DS9 episode), it seems to fit the background as a celebrated battle between the Klingons and the Romulans.

A brief but ultimately unsuccessful thawing in relations occurred in 2267 between the Federation, the Klingon Empire, and the Romulan Empire, with the founding of a jointly-managed colony on Nimbus III. Dubbed the "planet of galactic peace," the colony quickly became an embarrassing failure for all three governments, although regular meetings between representatives did take place at the colony for at least the next 20 years. (Star Trek V: The Final Frontier)

Tensions between the Klingons and the Federation again came to a head in the 2280s with the revelation of the secret Project Genesis, a scientific program developing an advanced method of quickly terraforming worlds – but a method which also had great potential for causing destruction. The Klingons sent a Bird-of-Prey to covertly obtain the secrets of the Genesis Planet, while at the same time negotiating openly with the Federation. The Klingons planned to accuse the Federation of duplicity in developing Genesis as a weapon of awesome power and using the negotiations as a cover. (Star Trek III: The Search for Spock) However, when the crew of the USS Enterprise, commanded by James T. Kirk, managed to capture the Bird-of-Prey, the Klingon ambassador proclaimed a vendetta against Kirk, vowing, "there shall be no peace so long as Kirk lives!" (Star Trek IV: The Voyage Home)

Détente and peace

Although negotiations had proceeded intermittently since the imposition of the Organian Peace Treaty, no major progress was made in establishing any firm relationship between the two powers. The most notable meeting, however, were a series of negotiations at the Korvat colony in 2289, where Federation mediator Curzon Dax met with Kang. No lasting agreement was reached at this meeting, but Dax did manage to gain grudging respect from the Klingons and establish a lasting rapport. (DS9: "Blood Oath")

In 2293, Gorkon, Chancellor of the Klingon High Council, raises a toast to "the Undiscovered Country - the future..."

The situation abruptly changed with the explosion of the Klingon moon of Praxis in 2293. The disaster caused major problems for the Klingon economy and military, as well as a major ecological crisis on Qo'noS itself. The Chancellor of the Klingon High Council, Gorkon, took the controversial move of proposing a full peace treaty and establishing a process for dismantling the military fortifications and outposts along their mutual border – the military emplacements and warships that the Klingons could no longer afford.

However, peace would not come easily. While en route to a meeting with the Federation president on Earth, Gorkon was assassinated by Starfleet conspirators from the USS Enterprise-A, who were working in cooperation with Klingon counterparts who also opposed any peace treaty between the two enemies. Gorkon's daughter, Azetbur, was appointed as the new chancellor in her father's place, and despite enormous pressure from her advisers to abandon the peace initiative, she chose to press forward and see her father's vision fulfilled. The ensuing Khitomer Conference resulted in the signing of the Khitomer Accords, a treaty which became the foundation for peace between the Federation and the Klingon Empire. (Star Trek VI: The Undiscovered Country)

File:Ambassador quarter.jpg

The sacrifice of the USS Enterprise-C in 2344 proved instrumental in maintaining and expanding the détente between the Klingon Empire and the Federation.

The relationship between the two great powers, however, remained rocky for the next several decades. By the early 2340s, the two powers once again stood on the brink of war. However, a single courageous act by the crew of a Federation starship would finally change relations for the better. In 2344, the starship USS Enterprise-C responded to a distress signal from the colony on Narendra III, which was under attack by the Romulans. Despite overwhelming odds, the Enterprise-C rushed to the rescue, and the crew's conspicuous heroism in attempting to protect potential enemies left a lasting impression on the Klingons. (TNG: "Yesterday's Enterprise")

The mediator Riva gained fame for negotiating several treaties between the Federation and Klingon Empire; before Riva, there was no Klingon word for "peace-maker". (TNG: "Loud As A Whisper") By 2353, the Treaty of Alliance was signed, finally establishing a firm friendship between the two former enemies – just as the Organians had predicted almost eighty years before. (TNG: "Yesterday's Enterprise"; DS9: "The Way of the Warrior") The Klingons even joined the Federation in some fashion, some time after 2327 but before 2365. (TNG: "Samaritan Snare")

The comment on the Klingons being some part of the Federation made in "Samaritan Snare" may be in fact referring to the Treaty of Alliance creating a firm alliance between the two powers.

Civil war

Main article: Klingon Civil War

K'mpec, Chancellor of the Klingon High Council in 2367.

Despite the establishment of a full peace treaty with the Federation, the Empire would not remain at peace for very long. During the reign of Chancellor K'mpec (the longest-lived chancellor in Klingon history), two rival factions developed in the Klingon High Council. One, led by Gowron, favored continuing the peaceful relationship with the Federation, while the other, led by Duras, advocated setting an independent and aggressive policy. Duras was also secretly allied with Romulan interests who were seeking to split the Federation-Klingon alliance. By early 2367, the two factions were on the verge of starting a new civil war. (TNG: "Reunion")

Although Duras was killed by Worf and his relationship with the Romulans exposed, Duras's sisters, Lursa and B'Etor continued the struggle in their brother's place. They presented Toral, the illegitimate son of Duras, to challenge Gowron for leadership of the Council. Because the majority of the Council had been corrupted by the House of Duras, they sided with the Duras sisters and walked out of the Council when Arbiter of Succession Jean-Luc Picard rejected Toral's claim, making official the division of the Empire. (TNG: "Redemption")


The First City on Qo'noS burns during the Klingon Civil War in early 2368.

The civil war, when it finally broke out, was as bold and bloody as any other conflict in Klingon history. The warriors of the Empire threw themselves into the fight with typical zeal – for example, Kurn was heard to shout, "Our time for glory is here!" In the first three engagements, the forces allied with the Duras family decisively defeated Gowron's allies. However, it was not generally realized at the time that the Duras forces were secretly receiving material aid from the Romulan Empire. The Romulans hoped that a victorious Duras family would end the Federation-Klingon alliance and create a new Romulan-Klingon alliance to shift the balance of power in the quadrant.

However, interests in Starfleet recognized the probability that the Romulans were interfering in the conflict. Jean-Luc Picard and the USS Enterprise-D led a fleet of starships to the Romulan-Klingon border, establishing a blockade and preventing the Romulans from sending the Duras forces further assistance. When the Romulan connection was finally revealed, support quickly fell away from the Duras family, and Gowron successfully reunited the Empire under his leadership. (TNG: "Redemption II")

Renewed hostilities

The Klingon flagship, Negh'Var attacks Deep Space 9 in early 2372.

The Federation-Klingon alliance would be sorely tested in the 2370s, after the Federation made first contact with the Dominion in the Gamma Quadrant. The leaders of the Dominion, the Founders, had the express goal of conquering all of the powers of the Alpha Quadrant in order to prevent them from threatening the Great Link. (DS9: "The Search, Part II") In late 2371, the Dominion captured General Martok, a trusted adviser to Gowron, and replaced him with a shapeshifter impersonator. (DS9: "Apocalypse Rising", "In Purgatory's Shadow")

The Changeling posing as Martok convinced Gowron that the recent civilian uprising in the Cardassian Union had been engineered and supported by the Dominion, and that the uprising heralded an imminent invasion by the Dominion into the Alpha Quadrant. To prevent this invasion from occurring, Gowron launched a massive assault against the Cardassian Empire in early 2372 with the goal of conquering all Cardassian territory to ensure that it could not be taken by the Dominion.

When the Federation Council protested Gowron's actions, Gowron took it as a betrayal of the alliance and withdrew from the Khitomer Accords, ending the Federation-Klingon alliance. Although no declaration of official hostilities was made, a state of near-war developed between the two powers; the Klingons even launched a preemptive attack against the Federation outpost Deep Space 9 in order to capture the remaining free members of the Cardassian Detapa Council. However, Deep Space 9 captain Benjamin Sisko pointed out to Gowron that a war between the Federation, the Klingons, and the Cardassians was exactly what the Dominion wanted – a divided Alpha Quadrant that would be ripe for conquest in the future. Faced with this reasoning, Gowron called an end to the invasion and halted the attack against DS9. (DS9: "The Way of the Warrior")

However, peace would not return. The Federation had refused to fight alongside their allies and had actually sided against them in battle, and the Klingons could not forgive or forget this transgression easily. A tense stand-off developed over the next year, with the Klingons attempting to make political inroads against both the Cardassians and the Federation to justify their offensives. (DS9: "Sons of Mogh", "Rules of Engagement")

Finally, in late 2372 and at the Martok Changeling's suggestion, Gowron demanded that the Federation relinquish claims to a number of territories along their mutual border, or face war. When the Federation Council refused the demands, the Empire launched a massive invasion of the Federation. The Federation-Klingon War (2372-73) was brutal, but short – only a few weeks after it began, Gowron called an end to the conflict after a Starfleet covert ops team revealed that Martok was actually a shapeshifter, and the entire war had been engineered to divide the two former allies. (DS9: "Apocalypse Rising")

The Dominion War

Facing the imminent threat of a Dominion attack, Klingon Chancellor Gowron re-signs the Khitomer Accords in 2373.

When the Dominion annexed the Cardassian Union in mid-2373, the Klingons were quickly defeated by the Jem'Hadar and driven from all of their Cardassian conquests. Faced with the prospect of a larger war against a much more powerful enemy, Gowron agreed to re-sign the Khitomer Accords and renew the alliance with the Federation. In addition, a detachment of Klingon soldiers was assigned to Deep Space 9, commanded by the real Martok, who had been rescued from a Dominion internment camp (DS9: "By Inferno's Light")

File:Operation return klingons.jpg

Klingon forces relieve the Federation fleet during Operation Return in 2374.

The Empire and the Federation would ultimately fight side by side in the ensuing Dominion War that broke out in late 2373; many of the most important engagements of the war were conducted in concert, including the Second Battle of Deep Space 9, the attack on Torros III, and Operation Return. (DS9: "Call to Arms", "Sacrifice of Angels")

The anti-Dominion alliance gained new, unlikely allies in mid-2374 when the Romulan Empire declared war against the Dominion. Although the Romulans and the Klingons both harbored deep hatred for the other, the two former enemies managed to put aside their differences in order to successfully fight the Dominion. (DS9: "Tears of the Prophets")

However, ultimate victory would eventually come at a very high price. When the Breen Confederacy entered the war in late 2375, the use of the previously-unknown energy dampening weapon effectively nullified the power of Starfleet and the Romulan forces, leaving the Klingons to fight on their own, outnumbered twenty to one. Rather than fight a holding action, however, Gowron ordered that Martok launch a full-scale offensive against the enemy, claiming that they had the advantage of surprise. (DS9: "When It Rains...")

Ostensibly, Gowron hoped to achieve quick victory against the Dominion and claim all of the glory for the Empire in winning the war without the assistance of the Federation or the Romulans. But Gowron's real plan was much more subversive and political. Gowron feared the growing popularity of Martok, who had commanded the Klingon forces on the front lines and was rapidly gaining heroic status among the soldiers of the Empire. Gowron hoped to reclaim some of that popularity for himself by personally commanding the Klingon war effort from Deep Space 9, and by discrediting Martok in sending him on numerous hopeless missions.

When no other Klingons would protest, Worf challenged Gowron to single combat, claiming that Gowron was a coward for jeopardizing the very existence of the Empire (and indeed the safety of the entire Alpha Quadrant) in order to satisfy his need for political security. Worf killed Gowron in the fight, thus claiming the right to rule the Empire himself. However, Worf declined the position and nominated Martok instead. (DS9: "Tacking Into the Wind")

File:Battle of Cardassia 5.jpg

With the signing of the Treaty of Bajor, the Dominion War is finally ended in 2375.

Ultimately, the Empire would share in victory with the Federation and the Romulans after the final defeat of the Dominion at the Battle of Cardassia in late 2375. (DS9: "What You Leave Behind")

Section 31 estimated that the Klingons would not recover from their losses from the Dominion War until about 2385. (DS9: "Inter Arma Enim Silent Leges")

Alternate timelines

In an alternate timeline, the Klingons took control of Deep Space 9 after the death of the emissary Benjamin Sisko in 2372 (because the Bajorans interpreted this as sign against the Federation and tried to ally with the Cardassian Union). This timeline was avoided due to the intervention of Jake Sisko in 2422. (DS9: "The Visitor")

In Q's anti-time future, the Klingons had conquered the Romulan Star Empire by the late 24th century. (TNG: "All Good Things...")

In Daniels's alternate timeline, the Klingons (re)joined the Federation by the 26th century. (ENT: "Azati Prime")

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