Dominion cold war
The Dominion cold war was a period of events between the initial official first contact between the United Federation of Planets and the Dominion in late 2370, to the onset of the Dominion War three years later. The cold war was largely defined by repeated Dominion infiltration of various Alpha Quadrant powers, intending to unravel the political alliances that had largely kept the quadrant in peace. Several of these infiltrations were highly successful, triggering conflicts between major powers.

Prelude 
In 2369, the Federation discovered the Bajoran wormhole in the Denorios Belt. ()  Almost immediately thereafter, ships from various powers of the Alpha Quadrant began exploring and colonizing the Gamma Quadrant. The first Alpha Quadrant species to gain knowledge of the Dominion were the Ferengi in 2370, when they negotiated a trade agreement with the Karemma, an important mercantile member of the Dominion. ()

Further reports of the Dominion continued to trickle through to the Alpha Quadrant: the Skrreea related that their former oppressors, the T-Rogorans had recently been conquered by the Dominion. Also, a Yaderan named Rurigan informed Deep Space 9 personnel that his homeworld Yadera Prime had been conquered around 2340. ()

Contact 
During the Alpha Quadrant's colonization of the Gamma Quadrant, the Dominion had been collecting extensive intelligence on the major powers on the other side of the wormhole, but remained elusive. In late 2370, official first contact was made when Commander Benjamin Sisko and Quark had been detained by the Jem'Hadar, alongside a Vorta, Eris, who claimed to be a refugee from the Dominion conquest of Kurill Prime. 

The Jem'Hadar had followed this up by destroying a number of ships and colonies in the Gamma Quadrant, including New Bajor colony. This news was delivered to Deep Space 9 by Third Talak'talan, along with the overt threat that the Dominion would no longer tolerate Alpha Quadrant encroachments into Dominion territory, which was perceived to be anything beyond the Gamma Quadrant terminus of the wormhole. 

In response, Starfleet dispatched the  , supported by the runabouts  and , both as a show of force and to recover Benjamin Sisko and the runabout . Although Sisko and his expedition were successfully retrieved aboard the Rio Grande, the Starfleet force had been intercepted by three Jem'Hadar attack ships. The former rapidly found themselves to be hopelessly outmatched by Dominion firepower, as it was capable of penetrating Starfleet deflector shields with phased polaron beams. After retrieving Sisko, Starfleet attempted to withdraw. In a demonstration of Dominion resolve, one Jem'Hadar fighter rammed the Odysseys main deflector in a suicide run, destroying it with all hands. 

The remnants of the Starfleet force were permitted to withdraw. Back on Deep Space 9, Eris had been exposed by Quark as a Dominion agent, further revealing that the Jem'Hadar offensive was a ruse to plant her in Federation territory. Eris promptly beamed away, leaving the crew of the station with a warning: "You have no idea what's begun here". ()

Escalation 
After the destruction of the Odyssey, Starfleet assigned the , a prototype warship originally built to combat the Borg, to Deep Space 9. The Federation hoped to avoid all-out war, and so ordered Benjamin Sisko to take the Defiant into the Gamma Quadrant to seek out the Founders and convince them the Alpha Quadrant posed no threat. ()

After establishing contact with the Karemma, the Defiant was ambushed and captured by a Jem'Hadar squadron. The crew was detained on the  in the Omarion Nebula, where they were subjected to an elaborate simulation by Borath, intending to ascertain how the Alpha Quadrant powers would react to an overt attempt by the Dominion to establish an influential foothold in the Alpha Quadrant. The Dominion concluded they would be met by strong resistance and suspicion, with some preferring the destruction of the wormhole rather than accept Dominion influence. The Defiant was subsequently permitted to return to the Federation, though only through Odo's intervention. ()

Following these events, the Dominion threat seemed to recede, although the Federation and neighboring powers still regarded a Dominion invasion as only a matter of time, and began preparations. Deep Space 9 was heavily fortified, and, in mid-2371, a relay station and a series of listening posts were established on the far side of the wormhole to provide advance warning of a Dominion incursion. () 

Despite the constant Dominion threat, exploration and trade through the wormhole resumed. This exploration was not without its danger, however, as several Starfleet vessels went missing, presumed destroyed, in the Gamma Quadrant: the , the , and the . ()

Initial infiltration 
Dominion quiescence, however, was deceptive. Multiple Changeling agents were situating themselves at the highest environs of power in the Alpha Quadrant's powers. Though Starfleet and the Klingon Defense Forces were implementing sweeping security measures to combat Changeling infiltration, these measures proved to be ultimately ineffective, and were easily countered by the Changelings. ()

The Dominion soon prioritized the Romulan Tal Shiar and the Cardassian Obsidian Order as key targets to be eliminated. The Dominion learned of a plan concocted by Enabran Tain, former head of the Obsidian Order, to form a strategic alliance with the Tal Shiar, with the ultimate goal to cripple the Dominion by wiping out the Founders. A Changeling assumed the identity of Romulan Colonel Lovok as a guarantee that Tain's plan would be carried forward. In 2371, a secretly assembled fleet of Tal Shiar and Obsidian Order warships bombarded the Founders' homeworld, only to discover it was a trap. A large fleet of 150 Jem'Hadar fighters ambushed and destroyed the fleet at the Battle of the Omarion Nebula, crippling the Tal Shiar and eliminating the Obsidian Order altogether. ()

Shortly after the incident at the Omarion Nebula,  masquerading as Federation Ambassador Krajensky attempted to incite war between the Federation and the Tzenkethi. The Changeling sanctioned a mission based on false rumors the Tzenkethi were preparing aggressive moves toward Federation border colonies, and ordered the Defiant to present a show of force. While en route, the Changeling hijacked the ship, and attempted to use it to attack the Tzenkethi settlement on M'kemas III. The Defiant crew were able to neutralize the Changeling in time to avert war. ()

The Alpha Quadrant destabilizes 
The fall of the Obsidian Order following the Battle of the Omarion Nebula had left a power vacuum on Cardassia. The Cardassian Dissident Movement had taken advantage of the situation and managed to successfully topple the Cardassian Central Command in early 2372, restoring the authority of the civilian Detapa Council. Some time prior to this,  had infiltrated the Klingon Empire and assumed the identity of General Martok. 

Using this position, the Changeling convinced Chancellor Gowron that the Cardassian revolution could not have succeeded without Dominion involvement, and proposed a preemptive strike against the Cardassian Union to ensure the security of the empire. The Federation Council publicly condemned the invasion and refused to commit support, compelling Gowron to withdraw from the Khitomer Accords, shattering the Federation-Klingon Alliance. Captain Benjamin Sisko managed to preserve the Cardassian state's leadership by sheltering the Detapa Council on Deep Space 9, and withstanding the subsequent Klingon assault during the First Battle of Deep Space 9. ()

Despite pleas from Sisko that interstellar conflict was exactly what the Founders desired, Gowron ordered his forces to fortify their conquests in Cardassian territory, effectively continuing the Klingon-Cardassian War, arguably the most successful result of Dominion political machinations in the Alpha Quadrant. The war soon degenerated into a war of attrition, resulting in heavy casualties, devastating the Cardassian Union. 

Meanwhile, on Earth, a Changeling infiltrator detonated a bomb at the Antwerp Conference in mid-2372, shattering some two centuries of peace. Admiral Leyton, long convinced that Federation President Jaresh-Inyo was ill-prepared to face the Dominion threat, attempted a military coup d'etat with a cadre of loyal Starfleet officers and the unwitting collusion of Starfleet Academy's Red Squad. The coup was ultimately unsuccessful after the Defiant reached Earth with evidence of Leyton's conspiracy, averting a potential Federation civil war. ()

The Martok Changeling proceeded to manipulate Gowron into laying a revanchist claim to the Federation Archanis sector in late 2372. Following the Federation's refusal to leave Archanis, the  began. A Starfleet infiltration team exposed Martok as a Changeling and secured a ceasefire with the Klingons in early 2373, though tensions remained high including a Klingon attack on Ajilon Prime. ()

By mid-2373, the Klingon-Cardassian War had taken its toll. The infrastructure of the Cardassian Union had been severely weakened as Klingon ships marauded through their territory. The Maquis under the leadership of Michael Eddington had taken the opportunity to informally ally with the Klingons; they all but drove the Cardassians out of the Demilitarized Zone and were preparing to declare themselves an independent state. The Dominion was later indirectly aided when the Battle of Sector 001 saw the Borg inflict severe damage upon Starfleet's military capabilities. (; )

Shamed and humiliated by the repeated Cardassian defeats, Gul Dukat began conducting secret negotiations on behalf of the Cardassian Union to join the Dominion.

Dominion foothold 
Sapped by two years of conflict, Starfleet determined its depleted strength would be unable to resist a Dominion attack. In mid-2373, a large Dominion fleet was discovered hiding in a nebula in close proximity to the Bajoran wormhole. Starfleet enacted a contingency plan to permanently seal the wormhole using a phase-conjugate graviton beam. However, Deep Space 9 had been infiltrated a month earlier by a  posing as Doctor Julian Bashir. This Changeling sabotaged the beam to strengthen the wormhole instead, rendering it invulnerable to any form of explosives. ()

With their lifeline to the Gamma Quadrant secured, the Dominion invaded the Alpha Quadrant. However, rather than attacking Deep Space 9 and securing strategic control over passage through the wormhole, the first wave of Jem'Hadar warships set course for Cardassia. Gul Dukat publicly announced the Cardassian-Dominion alliance, with himself as its leader. The alliance was generally embraced by the Cardassian people, and Dukat made a public plea promising to restore Cardassian pride. He made good on his promise; in just three days, the Jem'Hadar forced the Klingons into full retreat and massacred the Maquis in the Demilitarized Zone. ()

Believing a Dominion attack to be imminent, Benjamin Sisko convinced Gowron to reinstate the Khitomer Accords. Starfleet and Klingon forces prepared to make a united stand at Deep Space 9, surprisingly joined by Romulan forces. Rather than launch a frontal offensive, the Bashir Changeling attempted to induce the Bajoran sun to supernova with a protomatter-trilithium bomb, potentially wiping out the station and the combined fleet. The Defiant successfully prevented the Changeling from succeeding. ()

Although open war did not begin immediately, violence along the Federation-Cardassian border escalated, with ships such as the Starfleet vessel  and the Klingon warship  being reported missing. Tensions with the Dominion rapidly grew over the following months. The Dominion began sending large weekly convoys of warships, troops and supplies to fortify the Cardassian Union. The Dominion also began undermining potential alliances to isolate the Federation and the Klingons; they signed nonaggression pacts with the Miradorn, the Tholian Assembly, the Bajoran Provisional Government and, most significantly, the Romulan Star Empire. ()

Open war 
For the Federation-Klingon Alliance, the strategic situation was severely deteriorating. With war considered inevitable, Starfleet resolved to permanently halt the Dominion convoys by mining the entrance to the wormhole with self-replicating mines, an act which was considered provocative enough to trigger open war. 

Indeed, Weyoun arrived on Deep Space 9 to deliver an ultimatum; either Sisko removed the mines, or the Dominion would take the station. Despite subsequent posturing, in which Weyoun agreed the Dominion could limit the convoys to medical and economic assistance, both sides knew that it was only a matter of time before war began. Only two days later, a large Dominion-Cardassian fleet won the Second Battle of Deep Space 9, though not before the minefield was activated and Sisko destroyed the station's computer systems. The diversion of Dominion ships allowed a Federation-Klingon task force to cross into Cardassian space and destroyed a Dominion shipyard at Torros III, dealing them an early strategic blow. 

The Dominion War had begun. ()

External links

de:Dominion-Konflikt
ja:連邦-ドミニオン冷戦
Conflicts
Federation