The war had been going on for about six months. When was it?

Given the brutal conduct of the Dominion in the past DS9 "The Quickening" springs to mind, any resistance movement amongst the population could have led to severe orbital bombardment or mass executions so Betazed likely surrendered instead of risk trying to fight a ground war when there were Dominion ships ready to bombard them at any moment. 2373–2375 - The Dominion War is fought. The Dominion War. He needed to talk with her about what had happened in the observation lounge; he wasn't going to tell her she had been out of line since she was smart enough to see she had come close to … As the war takes a better turn for the Federation, I don't recall any mention of when the planet was re-taken. The Dominion attacked from a sector that Starfleet Intelligence ignored, and they caught the Tenth Fleet out of position on a training exercise. The ENT-E has a role in liberating the planet. In the fictional Star Trek universe, the Dominion War is a conflict between the forces of the Dominion, Cardassian Union and, later, the Breen Confederacy against the Alpha Quadrant alliance of the United Federation of Planets, the Klingon Empire and, later, the Romulan Star Empire. In the Pale Moonlight (and to my mind, the best of all DS9 episodes), it is mentioned that the Dominion capture Betazed. The Enterprise E took part in the events of First Contact and Insurrection during the time period that Deep Space Nine was fighting the Dominion War. The Dominion Axis was comprised of the Dominion, Cardassian Union, and the Breen Confederacy.The Federation Alliance was comprised of the United Federation of Planets, Klingon Empire, and eventually the Romulan Star Empire. The Dominion War was a major conflict in the Alpha Quadrant that raged from 2373 to 2375 between the Dominion and the Federation Alliance.

(LUG RPG: The Dominion War Sourcebook: The Fires of Armageddon) Following the Battle of the Three Suns the Kalandra sector had finally fallen to the Alliance. As a result Betazed fell to the Dominion within ten hours. The planet was theirs in less than ten hours. Given the brutal conduct of the Dominion in the past DS9 "The Quickening" springs to mind, any resistance movement amongst the population could have led to severe orbital bombardment or mass executions so Betazed likely surrendered instead of risk trying to fight a ground war when there were Dominion ships ready to bombard them at any moment. The Liberation of Betazed was a Federation Alliance offensive against the Dominion held Betazed system during the Dominion War in 2375. "I wonder what this meeting's about," Deanna Troi was saying to Beverly Crusher as they walked into the observation lounge. His duty shift over, Will Riker was heading for Deanna's quarters. The missions of the ENT-E and crew are covered in various novels, such as the Dominion occupation of Betazed. The doctor's usually smiling expression was missing as the stresses of the war were getting to her. Their victory sent shock waves through the Alpha Quadrant, and put the Dominion within striking distance of Vulcan, Andor, Tellar, and possibly Earth itself.

Betazed's Fall. As the war takes a better turn for the Federation, I don't recall any mention of when the planet was re-taken. In 2374, the Dominion invaded Betazed.