Ulji Mundok(late 6th-early 7th century) was an illustrious military commander of Koguryo (277 BC–AD 668). From his childhood he was brave, patient and good at martial arts and compositions. He was in a high position of minister of the Koguryo government.
In 612 the country was invaded by a foreign aggression force both on land and sea. Refusing to learn lessons from their defeat in the earlier aggression war against Koguryo, the enemy mobilized a total of three million troops consisting of 1 133 800-strong combat force and their two-fold-stronger logistics force, and launched the invasion of Koguryo in January. They intended to complete the war speedily by making the most of their numerical superiority.
Ulji Mundok, who was the general commander of the Koguryo army, foresaw the tactics of the enemy. He made sure that the main defence line was built up. Then, by smart command of the warfare, he foiled the enemy offensive by giving them a colossal loss.
Frustrated at their failure to conquer Koguryo by a surprise offensive and at the dragging on of the war, the enemy formed a detachment of 305 000 troops led by several commanders and thrust them deep into the inside of Koguryo. They planned to make their naval force join the land force to attack the North Pyongyang Fort of Koguryo from the sea and the land. The head of the enemy naval unit, however, launched the attack separately, carried away by his fever for fame, only to lose more than 30 000 troops and take a flight.
Ulji Mundok knew the enemy was going to take the North Pyongyang Fort by the advance of both the land and naval force, and proposed negotiation to the enemy head to have the inside knowledge of the enemy’s situation. Having negotiation single-handedly in the enemy camp, he found out the enemy’s weak points and worked out a plan of operations to employ the tactics of clean field and decoy and destroy the enemy’s scheme of aggression. Caught in the smart and thoroughgoing plot, the enemy force recklessly advanced as far as 12 kilometres up to the North Pyongyang Fort, which was the second capital of Koguryo where the general command was based.
There, however, they were confronted with strong defence positions of Koguryo. Already exhausted from the long march and battles, they now had little things to eat, and what further disheartened them was that their naval force had been vanquished to the smithereens. When they were in a cramped condition, Ulji Mundok wrote a satirical poem and sent it to the enemy commander.
Now the enemy commander knew they were caught in the tactics of Koguryo. Learning that they lost the initiative in the war already, they began to take flight in a hurry in terror. When they were halfway in the Salsu (river) to cross it, they suffered a heavy blow from the Koguryo force in ambush in the riverside. The Koguryo soldiers beat drums and gongs and made great shouts while firing a volley of arrows. Terrified and dispirited, the enemy troops fell to death in hordes, some hit by the arrows, some pierced by spears, some buried under the bodies of the dead, and some drowned.
Encouraged by Ulji’s exquisite and courageous strategy and tactics, the patriotic soldiers and people mowed down almost all the enemy force.
It was really a great victory, considering the fact that only 2 700 out of the 305 000 enemy troops reached the vicinity of the Ryodong Fort after fleeing 160 km away.
Historians call the victorious battle of Koguryo “Salsu Taechop” or “The Sweeping Victory at Salsu.”
Having suffered a colossal defeat in the battle, the enemy force began to retreat en masse the following day.
“The Sweeping Victory at Salsu” has been handed down generation after generation as a great battle demonstrating the burning patriotism of the Koguryo soldiers and civilians and the intelligence and wisdom of Ulji Mundok, along with his poem which reads:
Thy divine tactics have got through astronomy
Thy mystery tactics have mastered geography.
Thou have already performed great feats in battles