On 18 January 1591, King Naresuan the Great killed Prince Minchit Sra of Burma in a single elephant combat, marking the end of Burmese invasion. The battle is one of the epic moments in Thai military history and the day is now commemorated as Royal Thai Armed Forces Day.

Naresuan was born as Prince Naret on 25 April 1555, the son of King Maha Thammarachathirat and Queen Wisutkasat (herself daughter of a prominent noble, Maha Chakkrapat and Queen Sri Suriyothai). Growing up, the Prince was very close to his younger brother and elder sister. The three royal children had very different personalities, however; Naret was nicknamed The Black Prince for his strict character and devotion to discipline, Ekathotsarot (the younger brother) was known as The White Prince for his kind and considerate character, while Suphankanlaya (their elder sister) is remembered as the Golden Princess for her fair character and adherence to chivalric honour. The warm relationship between the three of them would be maintained for the rest of their lives; Naret and Ekathotsarot especially were not only brothers but friends and allies.

When Prince Naret was 8 years old, the Burmese King Bayinnaung invaded Siam. King Maha Thammarachathirat knew he would not be able to defend his lands, so he surrendered to Bayinnaung, acknowledging himself the Burmese Monarch’s vassal. To ensure the Siamese King’s loyalty, Bayinnaung took the young Princes Naret and Ekathotsarot as hostages back to Pegu. The Princes were treated kindly and with respect, and received extensive education. Among other things, Naret was educated in martial arts and strategy in Burmese and Portuguese styles. Despite his young age, Naret noted the great advantage Burmese military strategies and trainings had over Siamese ones, and he tried to absorb as much information as possible. Years later, the tactics he learnt while in captivity would help him to gain victory over the Burmese and re-gain independence for Siam.

In all, Naret and Ekathotsarot spent about 5 years as a prisoner of King Bayinnaung. By 1569, the Burmese King appeared to be certain of King Maha Thammarachathirat’s loyalty so he released the Princes. Promptly, Maha Thammarachathirat made Naret King of Phitsanulok as Naresuan – the name that he is mostly known under in modern times. For the next decade, both Maha Thammarachathirat and Naresuan appeared to have become loyal allies of King Bayinnaung. In 1581, King Bayinnaung died and was succeeded by his son, Nanda Baying.

The new King had no reasons to distrust Naresuan – now a prominent general – until 1583, when the late King Bayinnaung’s brother rebelled against him. Naresuan was supposed to quash the rebellion but Nanda Baying believed his response was too slow and half-hearted. He thus ordered his son, Minchit Sra, to kill Naresuan. The plan would have probably worked had it not been for two of Naresuan’s childhood friends back from his days of captivity; they warned him of the King’s plans and Naresuan had time to regroup his forces and march against Nanda Baying. When he learnt the opponents’ forces far outnumber his,

Naresuan initially wanted to retreat. However, Crown Prince Minchit Sra’s army followed him and so he had no choice but to fight: the two armies met at the Battle of Sittoung River – the first of the battles the Siamese King and Burmese Crown Prince would fight against each other. The battle ended in an unexpected victory for Naresuan, not least due to strategies he had learnt while in captivity in Burma. Minchit Sra was forced to retreat.

Siam was now de-facto independent from Burma and Naresuan devoted the next five years to mainly taking care of internal affairs. Among other things, he named his younger brother, Ekathotsarot the Uparaja – effectively, his co-ruler with equal powers and prerogatives. The tentative peace came to an end in 1590, when Minchit Sra – eager to avenge for his defeat six years earlier – tried to invade Siam. He expected Naresuan and Ekathotsarot to take defensive strategy; instead, the brothers responded with a swift counter-attack, defeating Minchit Sra’s armies. Defeated and humiliated again, the Burmese Crown Prince was forced to retreat again.

Nanda Baying was deeply dissatisfied by his son and heirs performance in Siam; he felt that until Minchit Sra defeats Naresuan, the stain of dishonour will not be cleaned. And so in 1592, he ordered his son to attack Siam again. Minchit Sra gathered a massive army and started the campaign. The timing was very unfortunate for Naresuan; he was preparing to conquer Cambodia and had to relocate his troops from one end of the country to the other. Hence, Minchit Sra’s initial progress through Siam met little to no resistance. The two armies finally met at Nong Sarai and the subsequent battle is commemorated as the Battle of Nong Sarai.

Naresuan knew his army was smaller in number and that however the battle ends a lot of lives will be lost. He thus decided to enter into a single combat with Minchit Sra to decide the outcome. Single battles, although not widespread, were not uncommon either. The rules were simple: a single champion of either army (typically, the Kings or Princes) would fight each other, usually to death. As per rules of chivalry, which were strictly adhered to in matters like this, the army of the defeated champion would then surrender to the mercy of the winner. In most cases, the soldiers were spared so single battles were effective ways to avoid considerable loss of human life – and considering both the army of Naresuan and the army of Minchit Sra actively deployed battle elephants, such loss was otherwise unavoidable.

Before a single battle could commence, however, an official challenge had to be issued – and therein was the problem. Keen not to let their Crown Prince come to a harm (especially known Naresuan was an excellent shooter), the Burmese had several fake Minchit Sras among their midst: they all resembled the Prince physically and were dressed like him. In the end, Naresuan recognised the Crown Prince by the decorations he was wearing – decorations only a Prince of blood was allowed to wear. Naresuan then addressed he Crown Prince: “My brother, why do you hide yourself in the shadows? Let us fight the elephant battle for our own honours. No future kings will do what we are going to do.” Minchit Sra was eager to restore his honour, he agreed; besides, he was younger and fitter than the Siamese King, his elephants were better trained, so he had an advantage.

The personal battle between Naresuan and Minchit Sra is known as Yuddhahatthi; it is one of the most memorable historical events in Thai history and has been highly romanticised. The King and the Crown Prince started the battle cautiously, testing each other’s strength. Minchit Sra’s better-trained elephant gave him an advantage and at one point, he came very close to killing Naresuan: his weapon narrowly missed the King’s neck and cut the side of his face. Still, Naresuan waiting for the right time; when the Crown Prince became too impatient and lost his guard, Naresuan quickly threw a blade, slashing Minchit Sra to death on the back of his elephant.

As had been agreed between the armies, the Burmese forces surrendered upon the death of their leader. Naresuan initially intended to execute all the Siamese soldiers who had fought on Minchit Sra’s side (from Lords who were still loyal to or vassals of the Burmese King) but was persuaded to spare their lives in exchange for promising they will henceforth be loyal to him. He then ordered to build a pagoda on the site of the personal battle as a victory monument. And it was truly a victory monument for the Burmese invasion ended with Minchit Sra’s death: devastated at the loss of his son and heir, and convinced it was a bad omen, Nanda Baying ordered to withdraw all forces from Siam.

Naresuan died in 1605. His brother and co-ruler Ekathotsarot succeeded him as King Sanpet III. Sanpet’s reign was short but relatively peaceful; he devoted most of his time and efforts to internal affairs, and to maintaining the large Kingdom his brother had built.