top of page

Strategic planning – The Battle of Thermopylae.

Historic Context.

An understanding of the events leading up to the Battle of Thermopylae is necessary to understand the real impact this event had on modern human history. The Achaemenid Empire or Persian Empire spread throughout the Middle East, reaching its peak in 500 BC.

The Persians had control of the region of Ionia, which was made up of 12 "Greek" cities (Miletus, Ephesus, Focea, Colophon...), Persian control was not burdensome since it allowed each city to preserve its institutions and customs. Not satisfied with this, the inhabitants of Ionia wanted to free themselves from Persian rule to regain sovereignty over their cities, so they began the IONIAN REVOLT in 499 BC, seeking to weaken the empire through guerrilla warfare; Seeing that they did not obtain the desired results, the Ionian rebels requested the help of mainland Greece, receiving the support of ATHENS and ERETRIA, thus giving rise to the first large-scale conflict between the mainland Greek cities and the Persian empire.

The Persian city of Sardes was burned by the Ionians, supported by the Athenians in 499 BC; causing this a negative impact on the Achaemenid empire. Persian King Darius I took about 6 years to put down the revolt; Once this was achieved, he swore to take revenge on all those who initiated and supported the revolt, with the continental Greek cities being his main objective to consummate his revenge; Darius I's dream was to see the city of Athens and its great temples in flames.

The first direct confrontation between the Greeks and Persians was the battle on the beaches of MARATHON, which was 40 kilometers from ATHENS, finally the Athenians would win since the Persians had great flaws in the planning of the battle, all this increased more and more the wrath of Darius I; the Persian king transmitted all that hatred to his son Xerxes I. Xerxes I, with a cooler head, began to plan the revenge of the Battle of Marathon, his main objective was to punish the Athenians for their meddling in the Ionian revolts. The Persians did not have a naval fleet large enough to transport the thousands of soldiers that would head into battle so they created a pontoon bridge with over 700 unique flax and papyrus boats to cross the Hellespont for access. to the mainland Greek polis.

The polis or cities of continental Greece were characterized by having different ways of seeing the world; so they rarely agreed, living in a permanent ideological conflict. Seeing the great threat that was approaching from the east, the Greek polis had to unite based on the premise “the enemy of my enemy is my friend”. It was the first time in history that two Greek armies fought together since Greece at that time was not a unified country but a group of city-states vying for regional supremacy; the main cities and staunchest rivals were Athens and Sparta.

Qualities of the commanders who led the battle.

Leonidas I.

Teamwork; eHe greatly values ​​teamwork because he considered that the life of each soldier depended directly on his partner; he managed to create and motivate a team of 300 Spartans to fight in sync. Work specialization; He believed in the "specialization" in the work because each and every one of his 300 soldiers had been trained as children for combat, being professionals in this area. While the soldiers of the other armies were not so well trained, they had to carry out other tasks in their community.

Resistance and confidence; Leonidas believed enormously in his team so he knew that he could withstand the attacks of a much larger army regardless of adversity, this allowed him to face the battle with his head held high and with the hope of victory.

Jerjes I.

Ambition; the Persian king wanted to reach Athens in any way possible for this reason he did not hesitate to create one of the largest armies in history to achieve his goal, it is said that he assigned more than 250,000 soldiers since he wanted to have an army vastly superior to his rival [the "Greeks" did not manage to muster more than 10,000 soldiers]. Planning; the creation of the pontoon bridge over the Hellespont shows the real intention of Xerxes I to win regardless of the costs incurred; this bridge saved a great number of days by safely crossing the strait without the need for naval fleets; this work being one of the greatest of its time. Alliances; Xerxes I was not afraid to create strategic alliances with armies and/or people in order to achieve his primary objective, he was always open to listening to alternatives to win the battle regardless of the paths to be followed, that is why he listened to Ephialtes and the end could give a favorable turn to the battle of Thermopylae.

Strategic planning. Mission

We are an army made up of 7,000 Greek soldiers in addition to the 300 best warriors of Sparta, we work tirelessly as a team to stop the advance of the more than 250,000 Persian soldiers commanded by King Xerxes I.


Stop the Achaemenid Empire from taking over and destroying mainland Greek cities.

SWOT analysis [Greek army]


  • The king of Sparta and leader of the Greek army LEONIDAS was one of the best warriors and strategists of the time.

  • Spartan soldiers were trained in combat arts since they were children, for this reason they were the best warriors in the world at that time.

  • Spartan soldiers were very well equipped for battle (weapons, shields, and armor).

  • The Spartan soldiers had an unshakable determination, as they followed their leader no matter what the obstacles.

  • The Greek generals knew very well the battlefield both on land and on the sea (Leonidas and Themistocles).

  • The Spartans had effective combat formations for the environment where the confrontation took place (phalanx formation).


  • The battlefield chosen by the Greeks (Thermopylae) only had a small and narrow road which could not be easily flanked.

  • Most Persian soldiers had no combat training as they were chosen at random.

  • The Persian infantry had little powerful and resistant rustic weapons.

  • Historically the Persians were used to fighting in open fields where they could use their cavalry to easily outflank their opponents, so terrain like Thermopylae was something new for them.

  • Weather conditions before the battle favored the Greek army as the Persians lost over 200 ships.


  • The Greek army only had about 7,000 soldiers while the Persians had more than 250,000 troops.

  • The Athenian navy was 1 to 6 inferior to the Persian naval fleet.

  • Unlike the Spartans, the other Greek soldiers (FOCENSES) did not have the training, courage and commitment necessary to face the Persian troops.


  • The Persian army was the largest at the time and vastly outnumbered the Greek army.

  • XERXES I's army had a large troop of well-trained archers.

  • The Persians had a group of 10,000 elite soldiers called "The Immortals".

  • Path that allows to flank the Spartan army.

  • Leaking of vital strategic information (Ephialtes betrayal).

Outcome of the battle.

Knowing that he was being flanked by the Persians, Leonidas sent the other Greek soldiers to their cities so that they could plan new defense strategies against the enormous threat that would reach the polis; the king of Sparta sacrificed himself along with his 300 soldiers giving the other “Greek” soldiers the opportunity to escape.

At the Battle of Thermopylae the Persians lost approximately 20,000 men, few considering the size of their army. The Athenians managed to evacuate their city before the imminent arrival of XERJES I's army that would finally fulfill his father's dream of seeing all of Athens burn.

Impact of the Battle of Thermopylae.

The heroic story of the 300 Spartans would inspire the Greeks who united as a nation forgetting their differences in order to face the great threat of the Persian empire, creating a nationalist spirit among the various Greek polis. Themistocles would lead the Greek army in the naval Battle of Salamis that would end up expelling all the Persians from mainland Greece.

The idea of ​​a nation was strengthened under the reign of Philip II of Macedon, who would unite all the Greek polis into a single state. Under one banner Philip's son named Alexander was born.

Under the flag of a united country ALEXANDER son of PHILIP II would destroy the Persian empire taking Greek culture to much of the world, teaching the vanquished Greek politics, literature, philosophy, art and laws, including democracy. All the cultural aspects that ALEXANDER THE GREAT defended would become the basis of Western civilization.

By. Andrés Felipe Salcedo Gutiérrez.


bottom of page