"The Battle" is another of those episodes that holds a pretty curious legacy in Next Generation lore. On the one hand, it's unquestionably better and more relevant than a lot of its first season brethren. But it also exists, within the context of most of the rest of the series (aside from the seventh season sequel "Bloodlines"), curiously out of step, other than the fact that it redeems the Ferengi after their first appearance and sets them on their way to what we would know of them later.
There, you see how convoluted it is? Let's start untangling.
In this episode we explore crucial aspects of Picard's backstory, notably his first command, the Stargazer. This is another thing that sets Picard apart from his famous predecessor Kirk, not only the fact that he's older and more cerebral (and bald!), but that he was captain of a starship not named Enterprise. By 1987, when Next Generation debuted, Kirk had just received command of the Enterprise-A in 1986's The Voyage Home. He'd destroyed the refit version of the original in Search for Spock, of course, but still zipped around space in more or less continuous command of a ship called Enterprise for twenty-five years (through The Undiscovered Country).
So that means Picard had a starship before Enterprise. That's what this boils down to. That's what "The Battle" is all about. The curious thing is that after "The Battle," this is pretty much forgotten (in the books, not as such). The curious fact of his artificial heart becomes far more important later on, the subject of a far more memorable episode ("Tapestry").
Stargazer is lost thanks to Starfleet's first military encounter with the Ferengi, though it's a victory for Picard that ends up like a defeat. He loses his ship (though not before executing the nifty Picard Maneuver) and unwittingly gains a mortal enemy, Daimon Bok. Bok appears here and again in "Bloodlines," but I'm not sure anyone really thinks of this rivalry when considering Picard, the Ferengi, or Next Generation. Bok's obsession even in this episode is portrayed as counterintuitive to typical Ferengi (financial) interests, by the way.
For the record, even though "The Battle" is a far better Ferengi appearance than "The Last Outpost," it's still pretty awkward as far as establishing them. Bok is more the menace that the Ferengi were supposed to be (the new Klingons, conceptually), but Ferengi greed (like 1980s greed in general) is hard-pressed to be understood in his context. In fact, it's so hard to reconcile that another series entirely (Deep Space Nine) is forced to make up the difference, and arguably so many fans have already had their Ferengi explained via Next Generation that it may have already been too late.
So it's best to view "The Battle" as a Picard episode, an artifact from a time before the series moved into a different gear that still manages to differentiate one captain from his famous predecessor.
franchise * series * essential * character
Memory Alpha summary.