The last part of the compilation The Prince takes place on Sparta, leading up to the acclamation of Lysander as Imperator by the Navy and Marines when the CoDominium collapses. Originally this part was published as the novels Go Tell the Spartans (1991) och Prince of Sparta (1994), written by Jerry Pournelle and S.M. Stirling.
Sparta is a constitutional dual monarchy, one King taking external affairs, the other King being involved in the economy. Citizenship with the right to vote is an earned privilege, as in Heinlein's? Starship Troopers?. Citizens are also expected to join the militia, on the model of Swiss citizen-soldiers. Other than enforcing basic laws, education and military service, the government does not intervene in the lives of the people. Prosperity or starvation is the responsibility of the individual.
The underclass can attempt to become Citizens, and many do. For the rest, the usual populists try to organize them into a Movement. Paradoxically, Sparta's openness and political transparency makes it more vulnerable to such a Movement than a dictatorship such as Carlist Santiago. One such movement has a guerilla army of self-styled Helots...
Finally, with the CoDominium in collapse and all Earth authority vanished, the Generals and Admirals acclaim Lysander, now King of Sparta, as Imperator.