How could spartan society spread its influence across the greek peninsula while maintaining control of its slave population?

Question

The Spartans today are regarded as the greatest warriors in history. A true Spartan dreams of dying in battle, for a glorious death is the greatest glory a real man can ever know. Every man trains his body to the height of physical perfection, demonstrated by their muscle-toned physique and chiseled, god-like form. All of these trials are meant to forge boys into true men, and it is this attitude towards strength and a hatred of weakness that has immortalized them as warriors without peer. This is put to the test at the famous battle of Thermopylae that pitted king Spartacus and his legendary 300 against Xerxes and his Persian army. This "living god" dared to think himself the equal to his betters, and invaded Greece in an attempt to conquer the entire peninsula.

BUT THIS IS SPARTA!!!, and it would not be cowed by worthless, foreign dogs. After successfully defending the coastal pass of Thermopylae (the hot gates) against the Persians and killing Xerxes, the rest of the his army were so terrified that they all ran home. It earned Spartacus the moniker "God of War", proving that they were the greatest army in all of Greece. This has lit a fire inside him, and he has decided to turn his attention to conquering his neighbors and beyond, so that he could bring the glory of Sparta to the entire world.

There is a problem however. This society relies heavily on its large slave population, called helots. The slaves are responsible for farming and other things that are necessary to keep society running, but beneath the worth of a Spartan. This allows free men the time they need to spend their lives training. Much of the army's time was spent keeping slaves in check. This is partly why sparta has never expanded so far before. A slave rebellion was always imminent, and one occurring while all the Spartans were away fighting could be the end of this great state.

It is the right for those superior in mind and body to suppress their inferiors, for the way of the harsh world is for the strong to survive, and the weak to suffer what they will. Nevertheless, Sparta must expand if it is to achieve its manifest destiny. How Can king Spartacus accomplish this vision while keeping the slaves in check?

Answer 1

"If the mountain won't come to the prophet, then let's take the prophet to the mountain."

In other words, you Kratos have just proven how superior your Spartan training, your men, your army are. Let the young men of all Greek city states come to Sparta. Allow them the great honour of being allowed to train there while offering them the amazing privilege of becoming true Spartans and pledging their allegiance to you as the only price they have to pay. They are even allowed to bring their families and slaves with them once they pledged their allegiance, became true citizens.

In this way, the main part of your army never has to leave Sparta and thus your own slaves uncontrolled by them, while at the same time your number of citizens rises greatly regarding the most important kind of citizens young well-trained men willing to themselves and their newly earned skills to you. Put your own trustworthy soldiers established in battles as the one at the Thermopylai in charge over the new recruits mixed with young Spartans functioning as officers in the great army which will bring the gods of war's word to the rest of Greece. Let your 'foreign' soldiers in their first battles fight against any other state than their home state to avoid conflicting loyalties. Keeping the slaves in Sparta from murdering their own families who are their owners and slave keepers should keep them motivated and loyal. As they may bring their direct family with them, they should not run into a moral conflict of having to fight (or at least tolerate the fight) against their former home states later, as they and their families have now become Spartans - their new home to defend and fight for its glory.

Answer 2

Don't think Sparta, think Rome.

The slaves in time become eligible for citizenship. If they serve their time and do their duty they get to call themselves Spartan. All they have to do is prove themselves worthy.

Slaves can be slaves on the land, but you should also have slave battalions with higher status and faster routes to freedom. Administrative slaves who can read and write and answer only to government, who can become citizens after only a short service. A slave who is doomed to always be trampled under the feet of a society who cares naught for him will always be at risk of rebellion, but a slave who always has opportunity for advancement, for greater status, for freedom and citizenship, simply by keeping his head down and working will be far less of a risk.

Answer 3

Let's introduce a game changer.

An advancement in in agricultural technology would mean a reduction in slave population size, although not in overall population.

Why? Less need of manpower in the fields would represent the possibility to optimize some processes, having a part of these people to address them in a specialized way. This inevitably leads to a social advancement for some of them, if not for the majority.

This new class of people could become free, or at least not be considered a threat if left by itself. They would ultimately join Spartiates in war operations as light infantry.

In this scenario, not only Spartans could go on a war outside of their borders, they could also have changed their military tactics meanwhile.

Now, what kind of technological advancement do we know it might work for us? Well, it's a long shot, but I would play a Ctesibius of Alexandria and his hydraulic machines. It's still 200 years in the future but enough to push an industrial revolution using mechanical mills and looms.