Final answer:
The exact number of Persians killed by the 300 Spartans at the Battle of Thermopylae is not known; historical records are unclear but indicate significant casualties inflicted by the small Greek force.
Step-by-step explanation:
The exact number of Persians killed by the 300 Spartans is not known with certainty due to the historical sources available, which are often biased or exaggerated. However, during the Battle of Thermopylae in 480 BCE, a small force led by King Leonidas of Sparta, which included 300 Spartans, along with other Greek allies, held off a much larger Persian army under King Xerxes. This engagement was part of the larger Greco-Persian Wars, where Greek city-states resisted the advance of the Persian Empire. Although the Spartans were eventually overwhelmed after several days of fierce fighting due to a betrayal that allowed the Persians to outflank them, they managed to inflict substantial casualties on the Persian forces. The battle's significance lies in its strategic impact, as it delayed the Persian advance and allowed the Greek city-states to prepare for further defense, ultimately contributing to Greek victories in subsequent battles.