Ancient Sparta was a famously militaristic society. According to legend, healthy Spartan boys were raised as warriors from a young age, while babies born weak, sick, or deformed were killed at birth by tossing them down into a deep chasm. So, are these stories reliable, and did the Spartans actually have a pit of death?
Sparta did have a pit of death. It was known in Spartan times, as it is today, as Kaiadas, which roughly translates to the house of the dead. The Kaiadas cave lies on the slopes of Mount Taygetos near the village of Trypi in the Peloponnese region of southern Greece.
The remainder of this article will describe when and what the Spartans used the pit of death for. It will also provide a brief historical overview of the backdrop to these actions that might help better situate them in the context of their day.
When Did Sparta Use a Giant Pit?
Sparta used a giant pit between the 8th and 5th centuries B.C. This was ascertained by carbon dating the remains found at the bottom of the Kaiadas cave to the period between the two Messenian Wars of the 8th and 7th centuries B.C. and the peak of the Spartan state in the 5th century B.C.
The conquest of Messenian lands over the course of two wars was the pivotal event in the rise of Sparta as a Greek power. These events led to the rise of Sparta as a military power and the leader of the Greeks in battle. The myth of a Spartan martial culture, which extends to the present day, follows from it.
Messene was a Greek city-state located to the west of Sparta.  Capturing the people of Messenia, and making them Spartan slaves, allowed the Spartans to free up their citizenry from manual labor. This enabled the Spartans to maintain a professional army of citizens dedicated to full-time careers as soldiers.
However, keeping their large population of Messenian slaves in check was a permanent headache for the Spartans. To do so, they resorted to increasingly violent means. The classical philosopher and historian Plutarch describes Spartan death squads that roamed the countryside surrounding Sparta looking for escaped slaves to kill. 
Many of the remains found at the bottom of the pit of death are today thought to belong to Messenians killed or captured over the course of the Messenian Wars. Although these do not account for all the remains, they are a reasonable explanation for the extensive use of the pit of death across this period.
What Did the Spartans Use a Giant Pit For?
The Spartans used a giant pit to dispose of various enemies and condemned persons. These included captured enemy soldiers, such as the Messenians, and Spartan citizens or slaves sentenced to death for various crimes.
There is no evidence among the bodies in the Kaiadas cave that suggests it was used to dispose of unwanted Spartan babies. In fact, a study by the classicist Debby Sneed makes the case that abandoning disabled infants wasn’t accepted in ancient Greek culture. 
Later historians may have been misinformed about the supposed infanticide practices of the Spartans. Besides, several recorded instances of disabled Spartan adults throw some doubt on such claims.  Plutarch, for example, mentions an exceptionally short Spartan king who had impaired legs.
Ironically, the same historians who are the chief source of the idea of Spartan infanticide also make references to disabled adult Spartans. The same Plutarch who describes a stunted Spartan king also suggests that Spartans had to submit newborns for inspection to a council of elders. Only if they passed this trial would the infants be allowed to live to adulthood.
If anything, the use of the pit suggests a powerful taboo against actively taking life in ancient Greece. This explains why the dominant forms of capital punishment at the time were all indirect. The ancient Greeks executed their criminals either by the pit, forced exposure to the elements, or stipulated consumption of hemlock.
According to these arguments, parents of unwanted babies were much more likely to leave them to die by exposure than to actively take their lives by throwing them into the pit of death. However, other scholars point out that a lack of evidence is not evidence. By this logic, we cannot rule out whether the Spartans practiced infanticide or not based on a lack of evidence.
What Warranted Death Among the Spartans?
What warranted death among the Spartans was sacrilege, charges of betraying the Spartan nation, and cowardice in battle. Spartans also condemned to death criminals who had murdered Spartan citizens, mutinous slaves, and enemy combatants captured in war.
A key feature of the Spartan society and military was the importance given to religious matters. While most Greek states performed animal sacrifices before and after a battle, the Spartans were known to take the practice of animal sacrifice to extreme limits. They required frequent blood sacrifices, including for events such as crossing a river.
There are also famous instances when the Spartan army put religious matters above the business of war. They arrived too late to assist the combined Greek forces at the battle of Marathon. At the battle of Thermopylae, they put forward a token fighting force, as they were preoccupied with celebrating the festival of Apollo.
Based on the Spartans’ demonstrated commitment to their religious practices, it is understandable that they viewed sacrilege as a severe transgression. According to Spartan social norms, these transgressions deserved the death penalty.
Similarly, for a society built around a military cult, betrayal or cowardice in battle was an egregious crime for which the death sentence was considered a fitting verdict. Again there are recorded instances of Spartans deemed traitors being condemned to death.
When Dexagoridas, one of the commanders of the Spartan forces at the Siege of Gythium, surrendered the city to the Romans, he was killed by his fellow commander Gorgopas. Although the Spartans would still go on to lose the war, the incident shows that they would rather lose a battle than tolerate behavior seen as cowardly in their soldiers.
Finally, arrowheads and chainrings found among the bones of the Spartan’s victims in the pit of death suggest that mutinous slaves and enemy combatants were also regularly executed at the Kaiadas cave. In fact, enemy combatants make up the most significant number of victims’ remains discovered there.
The Spartans had a pit of death, into which they threw those condemned to death, such as cowards, traitors, murderers, rebellious slaves, and enemy soldiers.