Just finished reading Sparta at War. Its a decent treatment of the rise and fall of the military might of Sparta. The author speculates a bit much for my tastes. It left me hungry enough for more history of Sparta, so I'm reading A History of Sparta. Here we are given a much more precise definition of the sources and brief interpretations of them and the city-states history.
Interestingly, both books seem to gloss over Sparta's actual military deployment and the battles she fought. This is largely because most of the battles she fought were in the 600-400 BC ranges. This is when she earned her fierce reputation throughout the Greek world (extending then into Anatolia, Turkey). There are few written records of these days, if any.
But what seems clear something happened there, something extraordinary. For a city that vanished from the face of the earth during the Roman days (less than 700 Spartan citizens when she was absorbed into the Empire), her memory resonates and has done so for 2 and half thousand years. And something made Leonidas stay at the Hot Gates....
Maybe their deeds did echo for an eternity.