The Breen apparently attack Earth and cause damage to Starfleet command but are destroyed by Federation ships. Now obviously they didnt use the energy dampening weapon because otherwise the Alliance would have been aware of the weapon but this begs the question why didnt they use it?
The majority of the Federations fleets were near the front lines and the Federation had no idea that the Breen were about to strike with a sneak attack so why didnt the Breen blast the Federation fleet at Earth and cripple them all and basically launch a full scale attack on Earth, take out Earth and Starfleet command and as has always been said you cripple the Federation.
It makes no sense why the Breen didnt just outright annihilate Earth there and then. Taking out Earth would alone be the largest turning point in the war and would mean complete defeat of the Alliance by the Dominion.
Yet another boo boo by the writers. The Breen should never have been said to have attacked Earth.