I just finished listening to The Peloponnesian War by Tulane Professor Kenneth Harl (36 lectures produced by the Teaching Company). This war was waged between the Athenian Empire and Sparta and her allies from 431 to 404 BC. I highly recommend this program: Harl does an excellent job of bringing this era to life.
This war has many features: the rise of terror tactics, ruinous plagues, large-scale sieges, out-of-control popular assemblies, ruthless butchering of civilian populations, breakdown of morality, cataclysmic sea battles, unscrupulous politicians, wasted military opportunities, court intrigue with the Persians, and the collapse of Athens' "Golden Age."
This is the first time I'd returned to this era since 1969-70 when I studied this war as a student (and even read Thucydides in the original Greek). In the intervening four decades, I've found that my perspective has changed considerably.
In the late 1960s, against the backdrop of the Cold War, it was customary to see a democratic and vibrant Athens in the role of the United States, and a stolid and secretive Sparta as a proto-Soviet Union. It was all too easy to downplay Athens' slavery and aggressive colonialism and play up Sparta's adherence to strong military values and deep suspicions about the outside world.
This time around I saw Athens in a less favorable light, and Sparta in a more positive way.
Athens greatly exploited (often cruelly) the member cities of her empire. And she used the slaughter of civilians to intimidate both foes and wavering allies.
And Sparta, after all, did win the war. And she did it because she proved to be the more flexible: she was able to build a fleet (quite an achievement for a land-locked power) and defeat Athens at her strength — on sea.
Also, for all the glory of the Athenian democratic popular assembly, the leaders it produced (after Pericles) tended to be weak, vacillating, and corrupt. Many of the Spartan leaders, on the other hand, e.g., Brasidas and Lysander, turned out to be more flexible, imaginative, and effective.
As companion reading material, I read Victor Davis Hanson's book, A War Like No Other: How the Athenians and the Spartans Fought the Peloponnesian War. I also re-read Book VII of Thucycides' Peloponnesian War (which deals with the failed Sicilian Expedition).
Hanson does a fine job of exploring how the two sides waged war. I came to understand the details of hoplite warfare, Greek cavalry tactics, and how two-year long sieges were conducted. Especially eye-opening is his description of life (cramped conditions, darkness, stench) aboard a Greek trireme (ship) and the terror that must have been a part of naval combat.
For me, the saddest and most sobering part of this entire story is the saga of the Athenian Expedition to Sicily. I kept thinking, "Why?" If you want the whole cocktail of hubris, strategic over-reach, poor leadership, bad timing, meddling politicians, and the bloody annihilation of an entire navy and army, it's all right there for you in the Athenian attempt to subdue Syracuse.
All in all, I'd say there is much to be learned from these events of nearly two-and-a-half millennia ago that can be applied to understanding what is happening to today. That is, after all, one of the reasons one studies history.
History is loaded with creative analogies. Napoleon marching on Moscow
is really just project management. Mao waging a guerrilla war is like
launching an ad campaign. What ideas from history can you apply to a
current project? 
