King Yeongyang is known to have successfully repelled four major invasions of the Sui Dynasty of China between the late 6th century and the early 7th century. Emperor Wen Di of Sui humbly accepted his defeat in the first military campaign against Goguryeo in 598 and no longer waged war afterwards. But his son, Emperor Yang Di, who killed his own father and elder brother to take over the throne, was different. As the second emperor of Sui was firmly determined to conquer Goguryeo, the dark clouds of war hung heavy over the region again.
In 612, Sui invaded Goguryeo with more than one million troops by land and sea. The number of reserve forces in charge of transporting provisions doubled, and it took 40 days to just start off the massive troops. Like the first war between the two states, Goguryeo was, again, able to fend off the imposing Sui forces. The victory shined most remarkably in the Battle of Salsu led by renowned general Eulji Mundeok who is remembered as one of the greatest military figures in Korean history.
An advance Sui army with over 300-thousand troops was confident that it could easily take over the Pyongyang Castle. The Goguryeo general employed a strategy to pretend to surrender. It was not until the Chinese were allowed to advance close to Pyongyang that they realized they were trapped. They hurriedly retreated, trying to cross the Salsu River. But General Eulji Mundeok had already been waiting there. It is said that the general had built a dam on the river that made the water level shallow. While the Sui soldiers were crossing the river, the general opened the dam and released a huge amount of water to catch the enemy troops off guard. A large number of Sui soldiers were swept away by the sudden rush of the river. Goguryeo troops also chased the remaining Sui troops, killing them at will. Historical records say that only 27-hundred out of the 300-thousand troops survived and returned to China. Although outnumbered, Goguryeo troops were able to overwhelm the strong enemy. The Battle of Salsu is known as one of the most glorious military victories in Korean history.
Despite this painful loss, Sui invaded Goguryeo two more times, each in 613 and 614, only to suffer defeat. The series of unsuccessful and self-destructive military campaigns against Goguryeo dealt a serious blow to the Sui Dynasty. It began to crumble under internal conflict, which prompted its collapse in 618. In the same year, King Yeongyang died, ending his 28-year rule.
The king enhanced his kingdom’s status with the victories over Sui, but the series of wars also caused great damage to Goguryeo. The enormous consumption of national resources had been one of the decisive factors that contributed to the fall of Goguryeo decades later.