Battle of Cardassia
With Dominion forces stretched thin across the Federation, Klingon, and Romulan borders and disrupted by the Cardassian Rebellion, the Female Changeling in charge of the Dominion's offensive in the Alpha Quadrant withdrew all forces from the Federation, Klingon and Romulan territories under the assumption that the Alliance resolve was not strong enough to press the battle at any cost into Cardassian space. The Founder was gambling that by reverting to pre-war territories, the Dominion would be able to build up a defence perimeter, shorten its supply lines, become less vulnerable to hit and run attacks, and rebuild its forces more quickly. She could not have been more mistaken. The Alliance, seeing an opportunity to press home an attack and defeat the Dominion once and for all, massed an invasion fleet of many thousands of starships at Deep Space 9, and launched it not long after. 
During the space battle, increasing rebel activity inspired by Damar's continued uprising destroyed various communications installations around Cardassia Prime, cutting off Dominion forces with their fleet. Under orders from the Female Changeling, Jem'Hadar troops destroyed Lakarian City in mere moments, killing 2 million men, women and children as punishment for the uprising among the populace. This proved to be another costly blunder on the Founder's part. In retaliation, Cardassian forces everywhere switched sides, greatly aiding the Alliance forces. Infuriated at this betrayal, the Founder ordered the Jem'Hadar to wipe out all Cardassians. More than 800 million Cardassians would perish as result of this atrocity before the war was finished.
Although the Alliance was projected to lose over 40% of their ships, they pressed on to the Cardassian homeworld, completely surrounding it. They now faced the huge Dominion and Breen defense fleet which was perhaps tens of thousands strong, and reinforced by Cardassian space stations as well as the formidable orbital weapons platforms like those deployed at the First Battle of Chin'toka. Before the battle could be joined, Odo convinced the the Founder to surrender, ending the war.