I'm interested in this, especially with the take that interstellar communication and travel mandate a more loose hegemony than an imperial model. What I'm wondering if the characters are the crew of a ship in a task force, what is their overall mission and what sort of options would exist for having political impact on the setting? For example, diplomacy with barbarians and potentially forging other alliances. 

I mean, you say Peloponnesian War, and I think "Philip of Macedon" a few decades later. I'd definitely like to explore the dynamics here.

Also, what is the structure of the military? Highly professional or is there some element of patrician/wealthy citizen service along with commission purchase? It seems like exploration for potential resources through naval service as an officer, would there be an element of commercial gain to Naval service in this regard, such as the discovery of new resources for government/companies through system survey and exploration?