The main source that described the battle of Thermopylae is the book VII of Herodotus. He was a Greek historian, and in his book he generally favors the Greeks. But he also writes about the greatness of the Persian Empire. There are also some doubts in the story told by Herodotus. For example, in one part Herodotus states that 2. 6 million people were the total Persian armies in the battle. But modern scholars reject this claim and they state that the figures given are unrealistic and it is as the result of miscalculations or exaggerations that sources put to favor the victor side.
King Xeroxes was so frustrated because his father, Darius who attacked the Greeks in 490 BC, shamelessly defeated in the battle of Marathon. After the battle Darius wanted to reinforce and attack the Greeks again, but the rebellion in Egypt got his attentions off the Greeks and before he could deal with the Egyptian, he died in 486 BC. Xeroxes then crushed the Egyptian and turned his attention to the Greeks. He started his long term plan, which lasted for couple of years, to be prepared for the war. At that time even the Greeks knew that the battle is inevitable.
Xeroxes decided that Hellespont, which is a narrow strait, connecting the Aegean Sea to the Sea of Marmara, is the way that he could get to Greece. So he ordered that Hellespont should be bridged by ships so his army could cross to Europe. By early 480 the massive army of Persia was ready to invade Europe, and the preparation was complete. The Persian army crossed Hellespont on two bridges which were made of ships.
Athenians were aware of the Persian threat and they were preparing for the war with Persians in the middle of 480 BC. It was at 482 when Themistocles, who was an Athenian politician and general, suggested that the best way to defend against the Persian is by building triremes, which were an ancient vessel and a type of galley. But the Athenians did not have enough workers to defend against the enormous army of Persia so they asked the other Greek states for help. A congress met in the late autumn of 481 BC, and an alliance was formed between the Greek states. The congress was very important and remarkable because some of the states were in war at that time, so the alliance helps the union between the Greeks.
The congress met again in the spring of 480, and this time they decided to block Xeroxes advance to Europe. The congress sends the army containing 10, 000 hoplites, which were citizen-soldiers of Ancient Greek city-states who were primarily armed as spearmen and fought in phalanx formation, to The Vale of Tempe, which is a gorge in northern Thessaly, Greece, located between Olympus to the north and Ossa to the south. However the planed did not work and the army retreated because Alexander I of Macedon warned them that the Persian army is overwhelming and they could bypass them easily.
The Persian army was marching through Greece with the help of Greek spy in august of 480 BC. They were in luck because by the law Spartan army were forbidden to have military activity because of a festival called Carneia. It was also the Olympic Games season and it would have been doubly sacrilegious for the whole Spartan army to march to any war. Under this circumstances king Leonidas took 300 men and around 1, 000 Phoceans, which were the support troops, with the orders of the Ephors, leaders of ancient Sparta, and shared power with the Spartan kings to launch an expedition and gather as many Greek soldier as possible and await the arrival of the main Spartan army. Herodotus told a legend that Leonidas consulted Oracle at Delphi, the priestess at the Temple of Apollo at Delphi, before and the oracle told Leonidas that he is going to certain death, so Leonidas only took 300 men with a living son.
By the time Leonidas arrived at Thermopylae, he had more than 7, 000 men contingents from various cities. He chose to defend the narrowest part of the pass of Thermopylae called the “ middle gate” because there was a defensive wall constructed by Phocians in there. He was afraid that mountain track nearby Thermopylae could be used to outflank the pass, so he put around 1, 000 men on the heights.
Finally, the Persian army led by the god-king Xeroxes approached Thermopylae. The total number is unknown and Herodotus number is unrealistic. Modern scholars estimate the total number of Persian army had been around 70, 000 to 300, 000. At first Xeroxes wanted to negotiate with Leonidas, so he sent an emissary to him. Leonidas refused the offer of Persians to resettle in another area and in a famous response he said: “ come and take them”. After that the war became inevitable and after four days, which Xeroxes thought the Greeks were going to disperse, he sent his troops to kill Leonidas and crush his army.
At the first day of the battle, Xeroxes ordered five thousand archers to attack the Greeks with their arrows, but the bronze shield of the Greeks deflected the arrows and eventually no one got hurt. After Xeroxes realized that the archers could not to any damage to Leonidas army, he ordered Medes and Cissians, which were around 10, 000 soldiers to attack and bring prisoners before him. They Spartans and other Greeks crushed them with an easy victory. Xerxes then shocked by the result sent his best troops, the Immortals. They defeated horribly and had no more success than the other group.
The reason Spartans could defeat the Persian army so easily is the tactical advantage at Thermopylae. One of the reasons was that Persians were too many on numbers and the battlefield was too tight, and the only weapons that they had were daggers and short spears for hand to hand combat. Persians were not fighting the way they had been trained and they were not equipped for such close fighting so the Greek army wiped them out easily. Another reason could be that Greeks were fighting for their lands, and defending their homes and their family so they had more intangible edge. On the other hand, half of the Persian army was slaves and to make them fight the Greeks the commanders lashed them with whips.
On the second day of the battle, Xeroxes again sent some troops to attack the Greeks. After Greeks drew them off with light injuries, Xeroxes stopped and withdrew to his camp without any plan. However, everything changed at the end of the second day. His name was Ephialtes, which coming to mean nightmare in the Greek language, and he was a Trachinian traitor. Greed and rewards made him to betray the Greek army and informed Xeroxes of the mountain path around Thermopylae. After that a Persian army under command of a general named Hydarnes attacked the pass. The 1, 000 Phocians guarding the pass were surprised by the Persian attack and they retreat to higher grounds to regroup after a brief resistance. However the Persian army advanced through the pass and did not chase them.
On the third and final day of the battle,
