Once the Dominion achieved a foothold in the Alpha Quadrant via Gul Dukats betrayal of the Cardassians, many analysts claimed that war was inevitable. Starfleet had been gearing up for war for almost three years, but when the Dominion began bringing both warships and supply vessels through the wormhole several hundred at a time, it became clear that the Federation would soon face a foe that was all but impossible to defeat.
The mysterious disappearance of several Starships along the Dominion border made their intentions clear, but the most telling moment came when the Dominion began to secure non-aggression treaties with various Alpha Quadrant powers - most notably including the Romulans. Facing an opponent which grew stronger by the week whilst its own support faded, the Federation was left with little choice but to act. Some military strategists suggested an all-out surprise attack on the Dominion, but Federation ethics forbade such a course of action. Instead, it was decided to close the wormhole to further Dominion reinforcements.
It was hoped that this would provoke the Dominion into an attack on Deep Space Nine; Starfleet knew that the capabilities of the new weapons array on the station would be common knowledge after the Klingon attack, and hoped that this would make the Dominion commit a large force from the nearest fleet base. Capturing the station would cost the Dominion heavily, giving them a purely phyrric victory since the minefield operated independently of the station and would be virtually impossible to clear anyway.
Whilst the Dominion was occupied at the station, Starfleet planned to send a Federation-Klingon task force across the border into Dominion space to attack and destroy the shipyards at Taurus III, putting a significant dent in warship production. This fleet would then head back to the station and recapture it from the weakened fleet after only a few days under Dominion control. The overall outcome of the operation would be to inflict a heavy loss on the Dominion fleet and support system.
The first phase of the plan went exactly as expected - the minefield was completed and activated in time and the Dominion lost over fifty ships in the battle to capture Deep Space Nine, while the allies were able to destroy the shipyards almost without loss. Unfortunately, the fleet which set out to recapture the station was defeated and forced into retreat with heavy losses, a pattern which repeated itself many times over the next few months.
Nevertheless, the operation was considered a success by Starfleet. The wormhole remained closed, and although the station remained in Dominion hands it was able to contribute little to the war due to the sabotage undertaken by the crew when they abandoned it. Ultimately the stations recapture would become a priority which would lead to the "Valley of Death" battle, the first major allied victory in the war.
With the loss of Deep Space Nine to the Dominion, the Federation-Klingon alliance was placed in an increasingly precarious position. Although the entrance to the wormhole was mined, the Dominion was known to be working on methods to clear the obstruction and bring heavy reinforcements through from the Gamma Quadrant - a move that would surely make the war unwinnable. Captain Sisko developed a plan to attack and recapture Deep Space Nine using elements from several Federation fleets bolstered by a contingent of Klingon ships. These forces began to gather at Starbase 375 in preparation for the attack, but word was recieved from Deep Space Nine that the Cardassians had in fact discovered a method of disabling the minefield. Starfleet had only six hundred ships ready to go, while the Klingons had not yet committed any forces to the plan. Nevertheless, faced with the imminent arrival of Dominion forces from the Gamma Quadrant, Captain Sisko took what forces he had to hand and headed for Deep Space Nine. Unfortunately, the Federation fleet was intercepted on route by a Dominion fleet of over twelve hundred ships. Outnumbered two to one, the deadline set by the events at Deep Space Nine forced Captain Sisko to attack the Dominion fleet head on in an attempt to get whatever forces he could to the station before the minefield fell. Initially the Federation forces concentrated their attacks on the Cardassians, hoping to split them from the Jem'Hadar and divide the enemy. In the event the Dominion fleet offered such an opening only as a trap; nevertheless Captain Sisko threw every ship he had into the breach in an all out assault. The attack rapidly disintergrated into chaos; the Dominion pressed home their numerical advantage, inflicting massive losses on the Starfleet forces. The Federation fleet was beginning to crumble when the Klingons finally arrived; catching the Dominion unawares, a large fleet under General Martok smashed into the enemy flank. The Defiant used this oppurtunity to blast her way through the fleet and headed for Deep Space Nine at maximum warp speed. The Defiant arrived at Deep Space Nine just in time to see the minefield detonated by the Cardassians; Captain Sisko took his ship into the wormhole to try and at least hold up the Dominion reinforcements. At this point the wormhole aliens intervened, apparently curious about Siskos motivations. The Captain convinced the aliens to intervene in the war, and they deleted the oncoming fleet shortly before it reached the Alpha Quadrant. The Defiant emerged from the wormhole to learn that the Federation-Klingon fleet had won a stunning victory over the Dominion, forcing them into retreat. Faced with a mass assault on the station which would endanger the life of a Founder, the Dominion evacuated the station and pulled its forces back to Cardassian space. Gul Dukat, the Cardassian leader, became mentally unbalanced at the magnitude of his defeat and was left behind on the station. Captain Sisko won a bet by setting foot on Deep Space Nines promenade a full ten seconds before General Martok, to a rapturous welcome from the Bajorans.
The first year of the Dominion war consisted of two main phases; for the first six months the Allies were in a state of near constant retreat, loosing several major fleet actions to the Jem'Hadar. Throughout this period the initiative remained almost entirely with the Dominion. All that changed with the operation to retake Deep Space Nine; the Federation and Klingon fleets inflicted a major defeat on the Dominion forces, smashing a 1,200 ship fleet and recapturing the station as well as convincing the wormhole aliens to deal with a further several thousand Dominion ships attempting to reinforce the Alpha Quadrant invasion forces.
For the next six months the war entered something of a stand-off. Although fighting continued almost all along the front lines, including the Dominions invasion of Betazed, neither side made a concerted effort to push into the others territory again. Many in Starfleet advocated a policy of "containment" - recommending that Starfleet should build its forces up sufficiently to deter further Dominion attacks without launching offensives of the own. However, Starfleet Intelligence's assessments of the Dominions shipbuilding and Jem'Hadar breeding programmes indicated that the balance of power would inevitably tip heavily in their favour once again over the next year. The only possible way to win the war was to launch an all out invasion of Dominion territory. Unfortunately, the Federation and Klingon Empires combined lacked the forces to ensure success.
The entry of the Romulans into the war towards the end of the year changed that equation. With the Dominion now fighting simultaneously along the Klingon, Federation and Romulan borders their forces were being spread more thinly. The addition of Romulan forces also gave the Allies the added firepower needed to mount a full scale invasion. The Chin'toka system was chosen to be the site of the first major attack, largely because intelligence had assessed it as having minimal defences.
Unfortunately for the Allies, the Cardassians had developed an extremely powerful orbital defence grid for the Chin'toka system. Hundreds of weapon platforms orbited the planet, each carrying heavy phaser banks, five thousand plasma torpedoes and regenerative shielding. Aware of the problem, the Allied fleet attempted to get to the system before the grid could be completed and activated. Initially they succeeded; several dozen of the platforms were destroyed in the opening attack. However, as the fleet closed on the planet the system was activated. A fierce battle raged for some time, with many Allied vessels destroyed or badly damaged while the defence grid suffered few losses. Fortunately for the allies, the crew of the USS Defiant determined that the entire grid was powered from a single location, an asteroid in orbit of the planet. The asteroid was also protected by regenerative shields, but the Defiant was able to use her navigational deflector to imprint a Federation warp signature on the asteroids systems; the defence grid turned on its own power system, destroying it completely. In the aftermath of the space battle the fleet began a surface assault on the planet itself.
Although the Chin'toka battle was ultimately a success, it was a battle won more by luck than anything else. Had the Defiant not been able to disable the power system the fleet would certainly have had to retreat. On the other hand, the Cardassians new defence system has been demonstrated to have a critical flaw. Essentially, the huge effort put into developing and deploying this system has been wasted. Until the problem can be corrected, those planets which have been fitted with this model of defence grid will now have to be protected by Starships, which will further reduce the number of vessels available for offensive action. Fitting the weapon platforms with their own power systems will require a major re-design effort, one which cannot possibly be completed in less than six to twelve months. This may give the Allies a window of opportunity during which they can inflict heavy damage on the Dominion, perhaps even leading to a permanent shift of fortunes in the war.
When the Allies captured the Chin'Toka system at the end of 2374, one of the planets seized was AR-558. The Starfleet contingent which invaded the planet found that it housed a communications array, the largest in the entire sector. Starfleet realized it had a possible way to access Dominion communications over a wide area, gaining vital intelligence. Unfortunately, the Dominion was just as aware of the arrays importance. Even five months after the Chin'Toka invasion the entire system was a battleground, with space and surface battles on a daily basis. Starfleet ordered the USS Defiant to land some supplies on AR 558, scene of some of the fiercest ground fighting. The Defiant was attacked by a Jem'Hadar ship on the way in, but was able to destroy it and reach orbit safely. Captain Sisko beamed down to find the situation on the planet desperate. Starfleet regulations require troops to be rotated off the front lines after 90 days; those on AR 558 had spent five months on the planet without relief. Starfleet had assigned 150 troops to protect the array - they were now down to 42, having suffered 72% casualties. Those remaining were both physically and mentally exhausted. Communications within the unit were breaking down, resulting in friendly fire incidents; both senior officers had been killed, leaving Lieutenant Larkin in command. When the Defiant again came under attack, Captain Sisko chose to stay on the planet and take command of the situation. The Jem'Hadar landed troops some nine kilometres from the communications array and began to organize another attack. When the assault came, it at first appeared to be poorly executed and easily defeated - unfortunately, the Jem'Hadar were using holographic soldiers in order to provoke the Starfleet soldiers into opening fire and revealing their location and strength. Sensor jamming was common on the planet, so Captain Sisko sent out a three man scouting team to locate the enemy. Ensign Nog used his Ferengi hearing to locate the Jem'Hadar base three kilometres from the array. Unfortunately the scouting party came under attack, resulting in the death of Lieutenant Larkin and severe injury to Ensign Nog, who later lost half of his left leg. Meanwhile, Sisko was faced with constant attrition by anti-personnel mines within the compound. The Dominion had deployed devices nicknamed 'Houdinis'. These mines sit within subspace, rendering them invisible and all but impossible to detect. They reappear at random, killing whoever disturbed them. Meanwhile, Lieutenant Dax and one of the local Engineers was successful in disabling the Houdinis and gaining control of them. Commander Sisko moved all of the devices to the ravine leading from the Jem'Hadar camp to the communications array. When the Dominion forces launched their own attack they lost one third of their forces to the Houdinis. Despite this, the Jem'Hadar attack on the communications array pressed the Starfleet forces to their limit. There was no attempt at complex tactics - the Jem'Hadar simply attacked en masse. The fighting rapidly degenerated into bloody hand to hand combat, with casualties heavy on both sides. Despite being heavily outnumbered, somehow the Starfleet forces somehow held onto the array. Shortly afterwards, the USS Veracruz arrived with replacement troops. The wounded were evacuated to Starbase 371, leaving AR 558 in the hands of the reinforcements.
Ever since the Allies captured the Chin'toka system in 2374 the Dominion had been launching furious counter-attacks in a determined effort to force them back out of Cardassian space. All these attempts were unsuccessful, until the alliance between the Dominion and the Breen in late 2375. The Breen forces were reasonably powerful in themselves, but they had never been considered one of the Alpha Quadrants major powers, and were not expected to alter the balance of war markedly in favour of the Dominion. However, the calculations made by the Allies failed to take one important factor into account; the Breen had developed a weapons system which would change the balance of power in the war. Initially the battle went reasonably well for the Allies - the Breen ships were fast and agile, but proved to be highly vulnerable to heavy weaponry. Several Breen ships were destroyed in the opening volleys before they could even return a shot. However, when they did open fire the Breen weapon created a form of energy dampening field around their targets which rendered them completely without power. The Defiant was the first vessel hit - it immediately lost propulsion, shields, inertial dampers and weapons. Without the ability to defend itself the ship was a sitting duck, and the Breen used standard torpedoes to inflict massive damage within seconds. Captain Sisko ordered the crew to abandon ship shortly before the Defiant was destroyed. The rest of the Allied fleet fared little better - ship losses in the battle were almost 100%, although casualties were relatively light as the Dominion did not engage in its usual tactic of destroying the fleets escape pods; a measure apparently intended to allow the survivors to spread fear throughout the rest of the fleet. Although this engagement can only be considered to be a disaster, the seeds of yet another turnaround in the Allies fortunes were sown in the Chin'toka system. A single Klingon ship was struck by the Breen energy drainer, yet it not only survived but suffered no significant damage as a result. Investigation by the Allies showed that the only significant difference between this ship and the others was a recent modification to some of its onboard systems. The Klingons rapidly had over 1,500 ships repeat this modification, making them invulnerable to the Breen weapon. Unfortunately, the Federation and Romulan ships were not suitable for such changes. As a result, the Klingons bore the brunt of the war for several weeks. Ultimately, the Allies were able to mount a daring raid on a Dominion shipyard which allowed them to capture an example of the Breen weapon and work out how to circumvent it on all of their ships.
The Dominion war had more reverses of fortune than most, but perhaps the most significant of all was the capture by the Allies of a fully functional Dominion attack vessel, complete with both a new energy dampening weapon and the technical crew which had recently installed it. The Breens unique weapons technology had put the Allies in a critical situation; only the Klingon ships had been successfully modified to resist the device, leaving them to shoulder the burden of the war alone. With the Dominion firmly back on the offensive, the Cardassian resistance movement realized that desperate action was required. Damar led a group of Cardassian freedom fighters, assisted by Colonel Kira Nerys and Elim Garak, on a daring raid against a Dominion shipyard to capture an example of the Breen weapon. Once Starfleet had its hands on the weapon and its technical crew, they were quickly able to neutralize the effects. By this stage it appears that the Founder commanding the Dominions Alpha Quadrant forces had become deeply disillusioned with the conduct of the war. She decided to pull all Dominion forces back into Cardassian space, creating a defensive perimeter which she hoped the Allies would be unable to breach. Within this protected zone, the Dominion would create a vast fleet with which to launch an unstoppable offensive. The Allies recognized the danger and launched an all-out assault on Cardassian space as soon as they were able. At the same time the Cardassian rebellion began in earnest. A popular uprising on Cardassia put most of the Dominion facilities under attack. Frustrated by the what she saw as a betrayal, the Founder ordered Weyoun to take decisive action to end the uprising. Weyouns response was to destroy Lakarian city, killing two million Cardassian civilian men, women and children. In a public broadcast he threatened to destroy another major city for each rebel attack. The action did not have the result intended. As soon as news of the atrocity reached the battle, the Cardassian fleet turned on their Dominion allies with a vengeance. The Allies used the opportunity to launch a full attack on the Dominion fleets centre; finding themselves assaulted on all sides, the Dominion forces were destroyed or forced into retreat. When news reached the Founder, she ordered the Jem'Hadar on Cardassia to rampage across the planet, killing as many civilians as possible. She had all available Dominion forces pulled back for a last stand at Cardassia Prime, hoping the battle would be so costly for the Allies that it would deter them from ever making an aggressive move against the Dominion again. The Allies predicted that clearing the Dominion system would cost them 40% of the combined fleet, yet they had no real alternative but to press on with the operation. As they advanced on the system, the Cardassian rebellion mounted a desperate attack on the Founders headquarters. Weyoun had badly weakened the contingent of Jem'Hadar guarding the base in order to provide more troops for the assault on the civilian population, and the rebels were able to capture the Founder herself. Constable Odo convinced the Allies to allow him to go down to the surface of the planet and meet with the Founder. He linked with her, curing her of the disease which Section 31 had spread amongst their people and convincing her that the Federations intentions towards the Dominion remained honourable even after all it had endured. The Founder agreed to order a ceasefire and surrender herself to the Federation in return for Odos return to the Great Link to spread the cure and establish a new relationship with the 'Solids'. The final assault on Cardassia never came; the Allies landed unopposed to find themselves on a planet devastated by the Dominion. But the cost was high; thousands of Allied Starships were lost, and over eight hundred million Cardassians perished at Jem'Hadar hands.