Dominion War

The Dominion War was a two-year interstellar conflict fought between the Federation Alliance and the Dominion between 2373 and 2375. The war consumed the entire Alpha Quadrant in one of the most destructive and bloody conflicts in galactic history.

First Contact
With the discovery of the Bajoran wormhole in 2369, several of the Alpha Quadrant's regional powers began to send explorers to the distant Gamma Quadrant to seek out new trading partners and establish new colonies. Throughout 2370, rumors of a power known as the Dominion were heard from several sources, but it was not until later that year that first contact was established by Starfleet commander Benjamin Sisko of space station Deep Space 9. 

Initial contact with the Dominion proved to be disastrous for the Federation. As retaliation for claims of territorial violations, the Dominion took credit for the destruction of several ships that had gone missing in the Gamma Quadrant, and for the destruction of the New Bajor colony. Additionally, Commander Sisko was detained and held responsible for the Alpha Quadrant's alleged violations of Dominion territory. A successful rescue attempt was conducted by the crew of Deep Space 9 and the USS Odyssey (NCC-71832), the latter of which was destroyed in the operation. However, it was determined a short time later that Sisko's capture and subsequent escape were part of a Dominion plan to place a Vorta spy in the Alpha Quadrant. 

Cold War
With the Dominion threat now fully realized, Commander Sisko requested that the USS Defiant (NX-74205) (I) be pulled out of storage and assigned to Deep Space 9. The Defiant's first assignment was to venture into the Gamma Quadrant and attempt to convince the Founders of the Dominion that the Federation posed no threat to them. To aid in this task, a special amendment was made to the Treaty of Algeron which permitted the Defiant to be equipped with a cloaking device. In return, the Federation would share all of its Dominion intelligence with the Romulan Star Empire. 

Although the Defiant was able to locate the Founders, the attempt to make peace proved to be unsuccessful. The Founders turned out to be a shape-shifting xenophobic species who believed that their survival depended on them imposing their order on the galaxy. 

Although the Dominion had made their intentions clear, the Founders had no desire to wage war on a united quadrant. To this end, the Dominion began a coordinated campaign to destabilize the Alpha Quadrant. In late-2371, the Dominion learned of a plan by Enabran Tain to combine Obsidian Order and Tal Shiar forces to attack the Founders' homeworld in the Omarion Nebula. Seeing an opportunity to put an end to the so-called "ruthless, efficient organizations," the Founders did everything they could to carry Tain's plan forward. When the combined Obsidian Order-Tal Shiar fleet arrived in orbit of the Founder's homeworld, it was quickly learned that the planet had been evacuated. At that point, a fleet of 150 Jem'Hadar fighters ambushed the fleet. The failure of Tain's plan resulted in the complete destruction of the Obsidian Order and the crippling of the Tal-Shiar. 

Several weeks later, the Dominion attempted to incite a war between the Federation and the Tzenkethi by having a Changeling posing as Federation Ambassador Krajensky hijack the Defiant and use it to attack a Tzenkethi colony. The attempt was thwarted by the newly promoted Captain Sisko and the Defiant crew. During this ordeal, Deep Space 9 security chief Odo became the first Changeling to ever harm another when he killed the Krajensky Changeling. 

By early-2372, the loss of the Obsidian Order finally allowed the Cardassian dissident movement to overthrow the Central Command and re-instate the Detapa Council. Believing that the change in government was engineered by the Dominion, the Klingon Empire dispatched a fleet to Deep Space 9 in preparation for an invasion of the Cardassian Union. When the Federation learned of the Klingon fleet's intentions, the Federation Council condemned the invasion. In response, Chancellor Gowron withdrew the Klingon Empire from the Khitomer Accords, ending the alliance between the two powers. Throughout the remainder of the year, the Klingons continued their campaign in Cardassian space, an act which left the Cardassian Union devastated. 

The Dominion threat had placed the Federation into a state of high suspicion and paranoia as well. In mid-2372, Starfleet vice admiral James Leyton used the threat of Changeling infiltration to attempt to overthrow the Federation government and instate martial law. By sabotaging a relay satellite on the far side of the Bajoran wormhole, Leyton was able to make it appear that a cloaked Dominion fleet was entering the Alpha Quadrant; thus giving him support for his coup. In the end, Captain Sisko was able to stop the coup and force Leyton to resign. 

In late-2372, the Klingon Empire, empowered by their war with the Cardassians, invoked "ancient claims" to the Archanis sector. Starfleet was given ten days to abandon the sector or face a war. At this time, Odo was extorted into returning to the Great Link to face judgement for killing the Krajensky Changeling a year earlier. While he was in the link, Odo realized the possibility that Chancellor Gowron had been replaced by a Changeling. 

By early-2373, the dispute over the Archanis sector had brought the Federation and the Klingon Empire to war. In an effort to expose the Gowron Changeling, Starfleet dispatched Captain Sisko, Lieutenant Commander Worf, Chief Miles O'Brien, and Odo to Ty'Gokor where Gowron would be presiding over the induction of new members into the Order of the Bat'leth. During the operation, it was realized that it was in fact General Martok who had been replaced. After the Martok Changeling was killed, the Klingons and the Federation returned to the negotiating table to end their war. 

Dominion Invasion
The Klingon-Cardassian War had left the Cardassian people broken and defeated. Frustrated with this situation, Gul Skrain Dukat sought out an alliance with the Dominion. Under the terms of this alliance, the Dominion was allowed to annex the Cardassian Union and Dukat was installed as its leader. The Dominion immediately began fortifying Cardassian space with weekly convoys of warships and Jem'Hadar soldiers, giving Dukat the military force he needed to drive the Klingons from Cardassian space and to put an end to the Maquis rebellion in the Demilitarized Zone.

After the Klingons were forced from Cardassia, Chancellor Gowron re-signed the Khitomer Accords and declared that the Empire and the Federation would stand side by side against the Dominion. 

Although a technical state of war did not yet exist, several skirmishes occurred near the Cardassian border over the next several months. Several ships, such as the and the USS Tian An Men were either destroyed or reported missing. Additionally, the Dominion began securing non-aggression pacts with several of Alpha Quadrants regional powers, including the Tholian Assembly, the Miradorn, the Bajorans, and perhaps most significantly, the Romulan Star Empire. This, combined with the Dominion's continued military build up, forced the Federation to act. Captain Sisko devised a plan to mine the entrance to the Bajoran wormhole, a move that was virtually guaranteed to lead to war. 

Total War Begins
When the crew of Deep Space 9 mined the entrance to the Bajoran wormhole with self-replicating mines to prevent more Dominion starships arriving from the Gamma Quadrant, the Dominion launched an assault against the station. Although the minefield was successfully deployed and activated, Benjamin Sisko and his crew were forced to abandon the station to Dominion forces. 

A Changeling obtained the detonation codes for the minefield after infiltrating Starfleet, although intervention by the Beta XII-A entity caused the death of the Changeling and those who were taking him to Terok Nor. (SS ST (Night of the Vulture))

For three months of the war, the Dominion was victorious in several battles, including in the Tyra system, when they destroyed ninety-eight out of a fleet of one hundred and twelve starships. When Starfleet discovered a Ketracel-white facility, Captain Sisko lead a successful mission to destroy it. 

Among the later Starfleet successes was an attack on a Dominion sensor array in the Argolis Cluster by the USS Defiant (NX-74205) (I). 

Starfleet was also able to enlist the aid of the Gorn Empire. 

Captain Sisko would later develop a plan to retake Deep Space 9 that was approved by Starfleet Command. However, when it was learned the minefield blocking the wormhole entrance would soon be destroyed by the Dominion, Starfleet was forced to deploy its forces sooner than expected and a fleet left Starbase 375 without Klingon forces and other fleets. While Captain Sisko's forces attacked a Dominion fleet that outnumbered them, Kira Nerys led a resistance movement on Terok Nor to disable the station and prevent the Dominion from destroying the minefield. The Dominion was successful in destroying the minefield although Captain Sisko was able to convince the Prophets to eliminate the Dominion reinforcements when they entered the wormhole, citing the risk to Bajor. With their reinforcements gone and their starships participating in the battle routed, the Female Changeling ordered a retreat of all Dominion forces to Cardassian space. 

The Prophets later blocked the entrances to the wormhole, meaning no further Dominion forces could be sent. 

With no possibility of assistance from the Gamma Quadrant, the Dominion was forced to enter into false peace talks with the Federation, putting forward a proposal to redefine the border between the Federation and the Cardassians, hoping to gain the Kabrel star system as they would be able to use Kabrel I's resources to develop large quantities of Ketracel-white. Their intentions were discovered by a group of genetically engineered Humans and peace talks failed. 

The Dominion later scored an impressive victory with the capture of Betazed, which threatened the safety of, Andor, Tellar and Alpha Centauri. Faced with this stunning defeat, and with more and more Starfleet personnel being killed, Benjamin Sisko began a plan to trick the Romulans into believing the Dominion was planning an invasion of their Empire. A forged recording of a meeting where Weyoun and Damar discussed the invasion was created, although Senator Vreenak discovered it was a forgery. Elim Garak planted an explosive that destroyed Vreenak's shuttle, making it seem Vreenak had discovered the Dominion's plan and was attempting to bring evidence of it back to Romulus. The Tal Shiar determined the imperfections were due to the recording surviving the explosion. The Romulans entered the war soon after and began assaults on several bases. 

Betazed was liberated from the Dominion in early 2375. 

The Romulans formed a new line of conflict with Dominion space on their border, in what became known as the Romulan Front. A bitter warzone, this would see a war of attrition form between Romulan and Dominion troops on a number of planets including Ogyas III. It was in this situation of barrage and counter-attack that the Dominion's uncaring attitude for their Cardassian allies became highly evident, with strategic setting of civilian 'shields' and disengaged supervision of Cardassian units evident. Serving in this front were future notable Cardassians Rugal Pa'Dar and Evek Temet. 

Among the troops used by the Romulans were Remans, who were used in the most dangerous battles, often suffering large casualties. Shinzon and Vkruk were among these troops, with Shinzon leading twelve successful campaigns during the war. Among these was the liberation of the Tal Shiar base on Goloroth from Jem'Hadar troops. (, SS ST (Twilight's Wrath))

With the Romulans bolstering the Allied forces, Starfleet chose Captain Sisko to plan the invasion of Cardassia. Sisko discovered the Chin'toka system was relatively undefended by Dominion starships, although the Cardassians were in the process of deploying powerful orbital weapon platforms to protect the system. The Allied forces reached the Chin'toka system just before the platforms were activated, managing to destroy several of them. However, once the platforms were activated several Allied starships were destroyed or disabled. The crew of the Defiant were able to locate the power source of the platforms on an asteroid and imprinted a false Federation warp signature on it, making the platforms fire on and destroy their own powersource, shutting down soon after. The Allies were able to secure the system and ground forces were deployed to two Chin'toka planets. 

Despite the capture of Chin'toka, the Allied forces were unable to fight their way further into Cardassian space as the Dominion was able to bottle them in the system. A Klingon fleet was repulsed when it attempted to destroy the Monac IV shipyards, although the crew of the were later able to destroy the Monac shipyards by using the Monac star to trigger a solar plasma ejection that engulfed and destroyed them. 

To treat their soldiers closer to the frontlines, the Romulans were granted permission by the Bajorans to establish a hospital on Derna. The Romulans also installed plasma torpedo launchers to protect the hospital, although the Bajorans deemed the launchers a threat to Bajor and began a blockade. Open conflict was averted when Admiral William Ross threatened Federation intervention. 

With the war continuing, the Female Changeling, who was now dying from a mysterious disease the Dominion could find no cure for, began negotiating with the Breen to become their newest allies. 

The arrival of the Breen angered Damar, who felt the Cardassian people were becoming sidelined. The lack of assistance to the Cardassian forces on Septimus III under Klingon attack convinced Damar to form a resistance movement to free Cardassia from the Dominion. 

The Breen later attacked Earth, severely damaging Starfleet Headquarters in San Francisco and also launched an offensive against the Allied forces in the Chin'toka system. The Breen used their energy dampening weapons to disable the Allied starships and soon destroyed them with conventional weapons. Among the starships lost was the Defiant. While the outlook seemed dire due to the Allies having no defenses against the Breen weapon, Damar's announcement that he had begun to attack Dominion targets made Captain Sisko remark that Damar may just be the key to save the Alpha Quadrant. 

It was later discovered that the Ki'tang, a Klingon starship, had not been affected by the energy dissipators due to a recalibration to its tritium intermix before the battle. General Martok ordered all starships in the Klingon fleet to be adjusted in the same way, making the Klingons the only state able to combat the Dominion. Chancellor Gowron assumed direct command of the Klingon fleet and, instead of holding a defensive position to hold off the Dominion while the Federation and Romulan fleets found a countermeasure to the Breen weapon, Gowron prepared to send Klingon starships on offensives into Dominion territory. Meanwhile, to assist Damar, Kira Nerys, Odo and Elim Garak were sent into Cardassian territory. 

Gowron proved to be a poor strategist and Klingon losses mounted, including a disastrous attack on Avenal VII. When Gowron announced he was planning an assault on Sarpedion V, a well defended Cardassian planet, Worf challenged Gowron for control of the Klingon Empire. Worf killed Gowron in honorable combat and installed Martok as the new Klingon chancellor. Elsewhere, Kira Nerys, Odo, Garak and Damar were able to steal a Breen weapon that was one of many being installed by the Breen on Jem'Hadar fighters. 

Kira, Garak and Odo returned to Deep Space 9 with the Breen weapon, allowing Starfleet to study it. Odo was close to death due to the virus he was infected with, although a cure was found by Julian Bashir and Miles O'Brien after luring Luther Sloan of Section 31 to the station. 

The Dominion soon moved to crush Damar's resistance movement, with Gul Revok betraying the fact Damar had approached him with the possibility of supporting the resistance. The Dominion and the Breen later destroyed all eighteen of the rebel bases, including those on Atbar Prime, Regulak IV, Simperia and Quinor VII. Kira, Damar and Garak sought refuge in Cardassia City in Enabran Tain's home, able to do very little with the resistance crushed. They soon realised that the Cardassian people had rallied behind him and that a popular uprising against the Dominion was possible. The Dominion, meanwhile, had learned that the Allies had devised a countermeasure to the Breen weapon, forcing them to fall back to Cardassian territory while they constructed more starships and breed more Jem'Hadar. The Allies later decided to make one final attack on the Dominion. 

End of the war
The Allies' assault began a few days later, when a large Allied invasion fleet left Deep Space 9 bound for Cardassia Prime. Sabotage by the Cardassians, meant the Dominion leaders were unable to communicate with their own fleet. However, a punishment for the sabotage, the Dominion destroyed Lakarian City and threatened more cities with destruction should the unrest continue.

After an opening stage that saw horrendous casualties on both sides, the Cardassian fleet would turn on their Dominion allies. This forced the Dominion to pull back to Cardassia Prime, forming a standstill between the fortress-fleet and the invading Allies. When they learned of the betrayal of the remaining Cardassian military, the Female Changeling would order the genocide of all Cardassians. On Cardassia Prime, Union planets and on all warzones still in action, the Jem'Hadar would shoot, burn or cut their way through all the men, woman and children they could find, civilian and military. On Prime alone eight hundred million Cardassians were murdered in the remaining hours of the war, though ragtag resistance movements and some military units managed to resist the marching murderers. As part of the policy of genocide, cities and buildings would be leveled, leaving Cardassia City in ruins. 

In the midst of the genocide, Damar's resistance cell was able to fight its way to Dominion Headquarters. The charge left all but Kira, Garak and a single Cardassian soldier dead, but they were able to capture the Female Changeling and Weyoun (the latter murdered by Garak for mocking Damar's demise). However despite her capture, the Changeling resisted the very idea of surrender. In an attempt to end the war, Odo beamed down and linked with the Female Changeling. In the union of the Great Link, he gave her the cure to the Changeling's disease. In return, the Female Changeling agreed to order the Jem'Hadar to surrender, and to be taken into custody by the Federation. 

The official surrender was signed on Deep Space 9, in the presence of Federation, Klingon, Romulan and Dominion officials. 

The Dominion forces were later escorted to the wormhole by Starfleet starships and they returned to the Gamma Quadrant. 

The Cardassians, however, would, despite their volte-face in the final stages of the war, not be welcomed with open arms by all members of the Federation coalition. In numerous warzones, in particular the Romulan Front, surviving Cardassian war units were taken as prisoners of war. These soldiers would be held for years before returning to their now-desolate homeland to find very few familiar faces still alive. 

Aftermath
Both sides suffered heavy loses in the war. Following the conflict the Federation's resources were spread thin not just in reconstruction of member worlds but also in aiding independent worlds affected by the war (seeking new allies and members in the process) and even aiding enemy worlds from the war, providing substantial assistance to help Cardassia recover from the final attacks from the Dominion. 

One of the worst events of the Dominion War was the Dominion attack on New Beijing. The Dominion had faulty intelligence that biogenic weapons were being developed there that were supposedly to be used to kill Jem'Hadar. The Dominion invaded the planet and at least five thousand of the inhabitants were killed. After the war, evidence surfaced that Section 31 may have arranged the massacre to convince Ethan Locken to join them. 

The Headquarters Allied Reconstruction Force (HARF) was established to rebuild Cardassia and treat the refugee situation after the war. Their headquarters would be built on the ruins of Coranum Sector in Cardassia City. 

A secondary work of HARF would be managing Cardassian and Federation DMZ-world populations, as well as other groups, in what was emerging as a refugee crisis in the early days after the war. As part of their work, HARF would recruit civilian traders and ships to visit all former subject and DMZ worlds. During this work, it would emerge - though never to be persecuted - that many of the worst-treated DMZ and subject world populations had massacred those Cardassians that had survived the Jem'Hadar genocide. 

In 2379, it was discovered that, during the Dominion War, the Federation had illegally armed the planet Tezwa with nadion weapons so that the Tezwans would be able to assist the Federation if the Jem'Hadar overran the Alpha Quadrant. 

In 2385 the Federation would finally begin to prepare to pull out Starfleet elements off Cardassia Prime, however the assassination of President Nanietta Bacco led to a disruption in the process during the tumultuous premiership of Ishan Anjar.