In the opening moments of this episode, the Enterprise has arrived at the Cardassian border to meet a Cardassian ship but when it arrives it opens fire on the Enterprise while her shields are still down. Despite the Cardassian ship getting in several opening volleys it is no match for a Galaxy class starship and it's shields are disabled in a heavy phaser attack from the Enterprise after the Cardassian ship refuses to answer hails.
It transpires that the Trager was responding to an attack on one of it's outposts by the Nebula class starship USS Phoenix under Benjamin Maxwell. The Nebula class like it's larger sibling ship the Galaxy class is able to defeat a Galor class even without it's shields being operative at the time as we see later in the episode via long range tactical displays.
