Goguryeo–Sui War
The Goguryeo–Sui War were a series of invasions launched by the Sui dynasty of China against Goguryeo, one of the Three Kingdoms of Korea, between AD 598 and AD 614. It resulted in the defeat of the Sui and was one of the pivotal factors in the collapse of the dynasty, which led to its overthrow by the Tang dynasty in AD 618.
Background
The Sui dynasty united China in AD 589, defeating the Chen dynasty and ending the division of the country that spanned almost 300 years. After the unification of China, Sui asserted its position as an overlord of neighbouring countries. However, in Goguryeo, one of the Three Kingdoms of Korea, Pyeongwon and his successor Yeongyang insisted on maintaining an equal relationship with the Sui dynasty.Emperor Wen of Sui was displeased with the challenge from Goguryeo, which continued small scale raiding into Sui's northern border. Emperor Wen sent diplomatic papers in 596 after Sui envoys spotted Goguryeo diplomats in the yurt of the Eastern Turk Khanate, demanding Goguryeo cancel any military alliance with the Turks, stop the annual raiding of Sui border regions, and acknowledge Sui as their overlord. After receiving this message, Yeongyang launched a joint preemptive invasion with the Malgal against the Chinese along the border in present-day Hebei province; It was the following year, 597.
Course of the war
First Invasion of 598
Emperor Wen ordered his fifth and youngest son, Yang Liang, and Admiral Zhou Luohou, to invade and conquer Goguryeo with an army and navy totaling 300,000, mostly composed of horse archers.Yang Liang's army faced the early rainy season when it reached Goguryeo. The unseasonably heavy rain made the army's progress almost impossible and hampered the transport of provisions. Constant attacks by Goguryeo forces and illness inflicted heavy casualties. Coming to the conclusion that the army could not achieve the objective on its own, Yang decided to combine with Zhou's naval fleet and proceed.
Zhou's navy also came across their own challenges, contending with rough seas, losing many ships despite staying close to the coastline. Whenever they anchored, Goguryeo detachments were present to attack the Sui sailors, and Sui fleet suffered a devastating loss.
Second Invasion of 612
Preparations
, when he won the throne in 604, built the Grand Canal connecting the north and south of China. The south, economic base of China, and the north, political base of China, were connected by the canal, allowing transportation of troops for the massive military campaign.After the construction of the canal, Emperor Yang ordered the enlisting of soldiers in 611. He instructed them to gather in present-day Beijing. The force gathered by year's end was one of the greatest in civilization according to the Book of Sui, which states that 1,133,000 troops were mobilized and that the support troops multiple times that number. The army began to depart in early 612, and due to its size, it took 40 days for all of them to depart. The long line of soldiers stretched for about 300 kilometers. The strength and losses may have been deflated by later Chinese historians.
Campaign in Manchuria
gave up the buffer zone that he had acquired after the war of 598, as the area was not suitable to face such a vast army. The Goguryeo troops retreated behind what is now known as the Liao River. A fortunate event for Goguryeo was that the river melted much sooner than usual. By the time Emperor Yang arrived, the ice had all melted. Undaunted, Emperor Yang ordered the construction of three bridges across the river. The bridges however, were too short to reach the opposite bank in another fortunate turn of events for the defenders, and Goguryeo's attack successfully held off the first assault. After the extension of the bridges however, the Sui forces succeeded in crossing the river, and the army surrounded the fortresses of Goguryeo.Emperor Yang ordered his generals before the campaigns not to make individual decisions regarding the movement of troops, but to report to him to receive instruction. This order hampered Sui strategy throughout the campaign. During the strategically important campaign against Yodong fortress, the general commanding the siege had to send a messenger to the emperor for the approval of the surrender. By the time the messenger returned, Goguryeo's troops were again ready to defend the fortress. Exploiting this flaw in the Sui system, Yodong and other castles of Goguryeo continued to hold on. By June, five months after the start of the campaign, not a single castle, fortress, or citadel has fallen to Sui. Emperor Yang felt that a fundamental change in strategy was needed to seize control of Korea.
Campaign against Pyongyang
The new strategy was to keep the fortresses of Goguryeo in Manchuria at bay, while sending a contingent of army and navy to take Pyongyang, Goguryeo's capital. An army contingent, allegedly with a strength of 305,000, and a naval fleet of some 120,000 were dispatched.Naval assault
The Sui navy reached the bay of the Daedong River before the army. Seeing that the Sui army had not arrived yet, Go Geonmu, commander of the defence army of Goguryeo at Pyeongyang and brother of King Yeongyang, sent what few troops remained in the capital to engage the Sui navy in battle. After an engagement, feigning defeat, Goguryeo troops retreated into the city. The Sui naval commander, Lai Huni, considering this was a chance to add to his merit, led a host of more than 40,000 to lay assault against Pyeongyang.When the Sui soldiers reached one of the outer castles, however, they found the wall empty and the gate open. Upon entering the castle, Lai, considering the engagement in the outskirts a decisive move of Goguryeo that failed, looted and destroyed the art and fortune of the outer castle.
Once the looting of the castle started, the death-defying corps of Goguryeo, consisting of 500 troops, ambushed the Sui troops. Confused and disoriented, Lai ran to the fleet at the sea, his legion reduced to mere thousands. Disheartened by his failure.
Sui army's campaign
The army contingent, led by generals Yu Zhongwen and Yuwen Shu, had their own problems. While the supply could be transported safely within China, once it reached Goguryeo territory, there was a danger of ambush by Goguryeo forces. Emperor Yang solved the problem by instructing each soldier to carry food for himself, which greatly increased each soldier's burden. Many resorted to discarding the food. By the time it had reached the Yalu River, the army's shortage of provisions was acute.Yeongyang decided to assess the strength of the Sui army by ordering his Commander Field Marshal Eulji Mundeok to fake a surrender and peace negotiation terms with the Sui generals. Generals Wu and Yuwen had their own secret order from Emperor Yang to seize Yeongyang or Eulji Mundeok if they should fall into their hands. However, the generals' advisers, notably the Assistant Director of the Right of the Department of State Affairs, Liu Shilong, convinced them it would be unwise to arrest negotiators from the opposing camp. They ultimately let Eulji return to Goguryeo and Yu Zhongwen later regretted his decision, attempting to lure Eulji Mundeok back. He sent a message that he wished to discuss things further but Eulji Mundeok, aware of Wu's intentions, did not comply.
The two generals argued about the next course of action, with Yu Zhongwen arguing strongly that Eulji Mundeok should be pursued. They did agree that the Goguryeo capital should be captured. Accordingly, the Sui troops began advancing south towards Pyeongyang. Eulji Mundeok maneuvered the Goguryeo troops so that they engaged the Sui army seven times a day, each time faking defeat and retreat. The strategy would draw the Sui army deeper south with the perception of victory. The Sui army eventually advanced to about 20 km from Pyeongyang. Yu Zhongwen later recognized that his advancing troops were suffering from exhaustion, and that fortifications of Pyeongyang made for an impossible campaign.
Yu was caught in a dilemma and could not decide on advance or retreat. Eulji Mundeok sent him for the occasion a poem:
Your divine plans have plumbed the heavens; Your subtle reckoning has spanned the earth. You win every battle, your military merit is great. Why then not be content and stop the war?When no response came, Eulji sent a representative. The plan now was to offer Emperor Yeongyang to Emperor Yang escort to submission if the Sui army would withdraw. Seizing this opportunity to retreat, Yu withdrew his troops towards Sui.