What significant event marked the end of the Second Persian invasion of Greece?

The significant event that marked the end of the Second Persian invasion of Greece was the death of Mardonius, who was the commander of the Persian forces during the invasion. This event took place at the Battle of Plataea in 479 BCE, where the Greek city-states united to confront the Persian army. The death of Mardonius was crucial because it not only led to the defeat of the Persian forces at Plataea but also symbolized the collapse of Persian military leadership and strategy in their campaign against Greece. Following this defeat, the remaining Persian troops retreated, marking the end of the Second Persian invasion and allowing the Greek city-states to effectively secure their independence and sovereignty.

The other events mentioned, such as the victory of the Spartans at Thermopylae, the burning of Athens in 480 BCE, and the formation of the Delian League, occurred in different contexts or times during the conflict, but it was Mardonius’ death that directly resulted in the conclusion of the invasion.