It is one of the most studied wars in history. The Peloponnesian War devastated Greece for over 30 years during the 5th century BC and had a lifelong effect on the Greek world. Athens and Sparta, two great city-states, fought incessantly for control of the Mediterranean. The once great empire of Athens would eventually be defeated, and its counterpart Sparta would also be severely weakened. This war would negatively affect Greece's world power and pave the way for an invasion by Macedonia later in the story. The Peloponnesian War would become an important part of the history of classical Greece and would forever change the lives of the Greek people. The animosity between the great city-states of Athens and Sparta was not always present. In fact, the two powers were practically allies by the beginning of the 5th century BC. During the Persian Wars, which began in 490 BC, Athens and Sparta resisted the invasion of Persia. The Greek-speaking cities that belonged to the Persian Empire along the western coast of modern-day Türkiye were in revolt, and the Athenians aided these revolts. As a result, the Persian king Darius the Great launched an invasion on Greece itself. This invasion culminated in the Battle of Marathon, which occurred that same year. Although outnumbered, Athens would defeat the Persian army in this battle. Persia retreated and would not invade Greece again for a decade. Until Xerxes, the next Persian king, would come to power. Xerxes came to power around 486 BC and intended to continue Persia's revenge against the Greek people. “This time they were determined to use overwhelming force, so in 481 BC Xerxes assembled an army of several hundred thousand infantry and a navy of… middle of paper… Eventually, Athenian-Spartan relations would reach the breaking point. A conflict known by many as the First Peloponnesian War began in 460 BC and lasted until 446 BC. It was a relatively mild struggle that occurred between the city states of Athens and Corinth, for the most part they were involved in the fighting with Athens, but in 446 BC a peace agreement was signed, commonly known as the “Thirty Years' Peace”. However, this peace did not last for thirty years his power at home built what are called the "Long Walls". These walls protected and connected Athens to its port of Peiraieus, and allowed the Athenians to withstand any siege Athenian strategy when the Spartans would attack them years later.