Goguryeo–Sui Wars

The Goguryeo–Sui Wars were a series of invasions that the Sui dynasty of China launched against Goguryeo, the largest of the Three Kingdoms of Korea, between 598 and 614 CE. Korean historians call them the Yeo–Su War (麗隋戰爭), from the first syllables of the two states' names; Chinese histories usually speak of Sui's expeditions to Liaodong.

There were four campaigns. In 598 Emperor Wen, the founder of the Sui, sent an army and a fleet that were defeated mostly by floods, disease and storms. In 612 his son Emperor Yang led one of the largest armies in pre-modern history in person. After months of failure at the fortress of Liaodong, he sent a strike force of 305,000 men towards Pyongyang, and almost all of it was destroyed at the Salsu River. Emperor Yang tried again in 613, but had to abandon the siege when a rebellion broke out behind him, and a fourth campaign in 614 ended with a face-saving submission by Goguryeo.

The wars mattered far beyond the battlefield. They exhausted the Sui state so badly that rebellions spread through China and the dynasty collapsed in 618, after only 37 years. For Korea, the victory preserved Goguryeo's independence for another half-century, and the general Eulji Mundeok became one of the great heroes of Korean national memory.

Goguryeo had existed for centuries by 600. From its heartland along the middle Yalu River it had expanded until it ruled Liaodong, much of Manchuria and the northern half of the Korean peninsula, with its capital at Pyongyang since 427. It was a kingdom of mountain fortresses: stone-walled strongholds on hills, often with water sources inside, where soldiers and farmers could shelter with their grain. Goguryeo also had influence over neighbouring peoples such as the Malgal and the Khitan.

China, by contrast, had been divided since the early fourth century between rival dynasties in the north and south. In 581 Yang Jian seized power in the north and founded the Sui dynasty; in 589 he conquered the southern Chen dynasty and reunified China. Known to history as Emperor Wen, he built a strong centralised state, and his son Yang Guang, Emperor Yang, completed the Grand Canal that linked the rich south with the north.

The Encyclopedia of Korean Culture describes the situation this way: for about a century and a half, East Asia had been a world of several great powers — the northern and southern Chinese dynasties, the steppe empires of the Rouran and later the Turks, the Tuyuhun in the west and Goguryeo in the north-east — each with its own sphere. A single empire ruling all of China upset that balance. The Sui expected Goguryeo to accept a place as a subordinate state; Goguryeo wanted to keep its own sphere of power.

Goguryeo had sent envoys and tribute to the Sui court, as it had to earlier Chinese dynasties, but the relationship was tense. According to the Book of Sui, when news came that Chen had fallen, Goguryeo's King Pyeongwon 'was greatly afraid, trained troops and stored grain'. In 597 Emperor Wen sent him a sharp letter: Goguryeo called itself a vassal but was not sincere; it pushed the Malgal around, blocked the Khitan from coming to Sui, and had secretly bribed Sui craftsmen and crossbowmen to defect.

The immediate trigger came in 598. The new king, Yeongyang, led more than 10,000 Malgal troops in a raid on Liaoxi, the land west of the Liao River; Wei Chong, the Sui commander at Yingzhou (modern Chaoyang), drove them back. Korean historians often interpret the raid as a pre-emptive strike against Sui forward bases. Emperor Wen, furious, stripped Yeongyang of his Sui titles and ordered an invasion.

The later wars had a further cause. In 607 Emperor Yang visited the tent of the Turkic ruler Qimin Khagan and found a Goguryeo envoy there. The possibility of an alliance between Goguryeo and the Turks alarmed the Sui court. The minister Pei Ju argued that Goguryeo occupied land that had once been Han commanderies and should not be allowed to remain 'a foreign domain'. Emperor Yang ordered the envoy to tell his king to come to court in person — or the emperor would come to 'tour his land' with the Turkish khagan. Yeongyang did not come, and preparations for war began in 611.

In the second lunar month of 598 Emperor Wen named his youngest son, Yang Liang, Prince of Han, together with Wang Shiji, as commanders of an army and navy of 300,000 men. The land army marched out through the Linyu Pass, near modern Shanhaiguan, at the start of summer. The rains had come early: roads turned to mud, supplies could not be brought up, food ran short, and an epidemic swept through the camps.

The fleet under Zhou Luohou sailed from Donglai on the Shandong peninsula towards Pyongyang, but storms scattered it and many ships sank. Some Korean accounts add that Goguryeo forces attacked the Sui ships and supply lines, but the early sources emphasise weather and disease. In the ninth month the army came home; the Book of Sui says 'eight or nine in ten had died'.

King Yeongyang then sent envoys to apologise, calling himself 'the dung-and-dirt subject of Liaodong', and Emperor Wen called off the war. When Baekje offered to guide a new invasion, the emperor refused, saying Goguryeo had already been pardoned. Goguryeo, hearing of the offer, raided Baekje's border. Both sides had avoided a long war, but nothing had really been settled.

Emperor Yang's preparations were enormous. Troops, ships, weapons and grain were gathered at Zhuo Commandery, whose seat stood at present-day Beijing, and the new Grand Canal was used to move supplies north. According to the Book of Sui the army that assembled in the first month of 612 numbered 1,133,800 fighting men, 'called two million', with twice as many men carrying supplies. It was divided into twenty-four armies with the emperor's guard. One army set out each day, forty li apart; it took forty days for all of them to leave, and the banners stretched, the text says, for 960 li.

Goguryeo did not meet this army in the open. The Encyclopedia of Korean Culture summarises its strategy: contest the river crossing, then withdraw into the fortresses, burn what could not be carried from the fields, and use small forces to harass the enemy and cut its long supply lines. In the third lunar month the Sui reached the Liao River. The first three pontoon bridges were built too short and stopped more than a zhang (about three metres) from the eastern bank; Sui soldiers who jumped into the water were cut down from the higher bank, and the general Mai Tiezhang was killed. Two days later the bridges were lengthened, the Sui crossed, defeated Goguryeo's army on the far bank and surrounded Liaodong fortress.

Liaodong, the old Han city of Xiangping near modern Liaoyang, did not fall. Emperor Yang had ordered his generals to report every move to him and to accept any surrender. Each time the fortress seemed about to fall, its defenders offered to surrender; the Sui generals sent riders to the emperor, and by the time the answer came back the walls had been repaired. In the sixth month Emperor Yang came to the fortress himself and berated his commanders, but the other Goguryeo fortresses held as well.

Meanwhile the Sui admiral Lai Hu'er brought a fleet from the Jiang–Huai region across the sea and up the Taedong River (then called the Pae). He won a first battle sixty li below Pyongyang and, against the advice of his deputy, led about 40,000 picked men straight into the city's outer walls. While his soldiers were plundering, Goguryeo troops led by the king's brother Go Geonmu — the Chinese sources mention 500 volunteers ready to die — sprang an ambush from an empty temple. Only a few thousand Sui soldiers got back to the ships, and the fleet withdrew to wait at the coast.

Unable to take the fortresses, Emperor Yang tried a quicker plan: nine armies, 305,000 men under Yu Zhongwen and Yuwen Shu, would bypass Liaodong and march on Pyongyang to meet the fleet. To avoid slow supply trains, each soldier was given a hundred days of food along with armour, weapons and tents — more than three shi in weight, far too much to carry. Soldiers who were threatened with death for throwing grain away buried it secretly in their tents, and by the halfway point food was already running out.

When the nine armies gathered west of the Yalu, the Goguryeo commander Eulji Mundeok came to their camp pretending to surrender, in order to see their condition for himself. Yu Zhongwen had secret orders to seize him, but the Sui official Liu Shilong persuaded him to let the envoy go. Yu soon regretted it and asked him to return; Eulji crossed back over the Yalu and did not come.

Now Eulji Mundeok used the Sui army's hunger against it. His troops fought and fell back again and again — the sources say Yuwen Shu 'won seven battles in one day' — drawing the Sui across the Salsu River until they camped on a hill 30 li from Pyongyang. There the Sui commanders saw that their men were exhausted, the city's walls were strong, and the fleet was not coming. Eulji sent Yu Zhongwen a short poem that has become famous: 'Your divine plans have searched the heavens; your clever reckoning has spanned the earth. Your victories are many and your merit is high — why not be content and stop?' He then offered, falsely, to bring the king to the emperor's court if the Sui withdrew.

The Sui took the chance to retreat in a square formation, attacked on all sides. On the 24th day of the seventh lunar month (late August 612 in the Gregorian calendar), when the army was half across the Salsu, Goguryeo troops struck its rear. The general Xin Shixiong was killed and all nine armies broke. The survivors fled to the Yalu, 450 li, in a single day and night. Of the 305,000 men who had crossed the Liao, only 2,700 returned to Liaodong. The Salsu is usually identified with the Chongchon River in North Korea. Emperor Yang ordered a general withdrawal the next day; the only gain of the whole campaign was a small Goguryeo outpost, Wuliluo, west of the Liao.

Emperor Yang would not accept defeat. In 613 he raised another army, recruiting volunteers called 'xiaoguo' (valiant soldiers), crossed the Liao in the fourth lunar month and attacked Liaodong again, this time allowing his generals to act on their own judgement. For more than twenty days Sui troops attacked day and night with siege towers, battering carts, scaling ladders and tunnels. The Sui began to build a ramp of more than a million earth-filled cloth bags as high as the walls, and eight-wheeled towers from which archers could shoot down into the city.

Before the final assault, news arrived that Yang Xuangan, son of the late chief minister Yang Su, had rebelled at Liyang, where he was in charge of shipping grain to the front, and was marching on the eastern capital Luoyang. Many sons of high officials had joined him. The vice-minister of war Husi Zheng, a friend of Yang Xuangan, fled to Goguryeo. Emperor Yang withdrew secretly by night, leaving mountains of equipment and his camps standing. The Goguryeo garrison, suspecting a trick, stayed inside for a day, then followed and attacked the rear guard near the Liao, killing several thousand. Yang Xuangan was defeated and killed two months later.

In 614 the emperor ordered a third campaign, even though revolts were now spreading across China and many conscripts never reached the assembly points. He reached Huaiyuan garrison west of the Liao in the seventh month, while Lai Hu'er's fleet defeated a Goguryeo army at Beisha fortress on the Liaodong peninsula and prepared to advance on Pyongyang. Goguryeo was exhausted too. King Yeongyang sent envoys offering to submit and handed over the defector Husi Zheng. Emperor Yang, 'greatly pleased', accepted and withdrew. Back in the capital he summoned the king to court; Yeongyang never came. Another campaign was ordered, but it was never launched.

For the Sui the wars were a disaster. Millions of men had been conscripted as soldiers or carriers; the Book of Sui records drought and epidemic in 612, 'especially severe in Shandong', the region that had supplied the campaigns. Bandit armies and rebels multiplied from 613 onwards. In 615 the Turks besieged Emperor Yang at Yanmen. He withdrew to Jiangdu (Yangzhou) in the south, and in 618 he was killed there by his own guards under Yuwen Huaji, son of the general Yuwen Shu. Li Yuan, Duke of Tang, founded the Tang dynasty the same year. Historians see the failed Goguryeo wars as one of the main causes, though not the only one, of the Sui collapse.

For Goguryeo, victory kept its independence and its hold on Liaodong. But it had also suffered years of war. The new king Yeongnyu, Go Geonmu — the same prince who had ambushed Lai Hu'er at Pyongyang — sought good relations with the early Tang. In 622 the two states exchanged prisoners, and Goguryeo sent back more than ten thousand Chinese captives. In 631 the Tang sent officials to bury the bones of Sui soldiers and destroyed a victory mound (gyeonggwan) that Goguryeo had built from the bodies of the dead.

Peace did not last. Emperor Taizong of Tang also expected Goguryeo's submission, and after the military leader Yeon Gaesomun killed King Yeongnyu in 642, relations collapsed. Taizong invaded in 645 and was stopped at Ansi fortress; after further wars, Tang and its ally Silla finally destroyed Goguryeo in 668. The Sui wars were thus the first round of a seventy-year struggle over north-east Asia.

Korean tradition has celebrated the victory for more than a thousand years. Kim Busik's Samguk sagi (1145) gives Eulji Mundeok one of its few biographies of Goguryeo figures and credits him with the victory. A shrine to him was built near Pyongyang in the Goryeo period, and another was ordered by King Sukjong of Joseon in 1680. His short poem to Yu Zhongwen is often counted among the oldest surviving poems by a Korean author, although it is written in Classical Chinese.

In 1908, as Korea was losing its sovereignty to Japan, the historian Sin Chaeho published a biography of Eulji Mundeok that presented him as a model of national spirit. Since then he has been a central figure of Korean national history. In South Korea, a main street in Seoul (Euljiro), a military decoration and a navy destroyer are named after him.

Chinese histories remember the wars differently: as a symbol of Emperor Yang's arrogance and misrule. The Book of Sui, compiled under the Tang, judged that he 'three times drove his chariots to Liaodong' while the people 'could not bear their lot', and quoted the saying 'war is like fire; if it is not contained it will burn itself out'. In modern times Goguryeo's history has also become the subject of dispute between Korean and Chinese scholars over whether Goguryeo belongs to Korean or Chinese history. Most international scholarship treats Goguryeo as one of the Three Kingdoms of Korea, while recognising that it ruled a multi-ethnic territory now largely in China.

Almost everything known about the wars comes from Chinese court historiography. The Book of Sui (Suishu) was compiled in the 630s under the Tang by a team led by Wei Zheng; its imperial annals give the campaigns in dated entries, and biographies of commanders such as Lai Hu'er, Zhou Luohou, Yuwen Shu and Xue Shixiong add details. Its chapter on the 'Eastern Barbarians' contains an account of Goguryeo. The Zizhi Tongjian, completed by Sima Guang in 1084, weaves these materials into a single narrative and sometimes notes contradictions between them.

No narrative from Goguryeo itself survives. The Goguryeo annals of the Samguk sagi, compiled in Goryeo in 1145, follow the Chinese accounts closely for these years, often word for word from the Zizhi Tongjian, though they change the point of view ('our army'). Some details found only in Korean tradition, such as a Goguryeo general Gang I-sik said to have led the 598 raid, appear in much later works and cannot be checked against early sources.

Dates in the Chinese annals are given by lunar month and a sexagenary day-name. They can be converted with historical calendar tables: for example, the Salsu battle, dated 'seventh month, renyin', falls on 26 August 612 in the Julian calendar (29 August in the proleptic Gregorian). Sometimes the texts are corrupt. The Book of Sui places the crossing of the Liao on a day-name that cannot exist in that month; Sima Guang had already pointed this out in his critical notes to the Zizhi Tongjian, and modern editors suggest a day in the fourth month instead. Even the year can vary: the Goguryeo chapter of the Book of Sui dates the first great campaign to the seventh year of Daye (611), when it was ordered, while the annals put the fighting in the eighth year (612).

Numbers are the biggest problem. The figure of 1,133,800 fighting men for 612 comes from Sui records, but some modern historians doubt that an army of that size could have been assembled, supplied and moved as described, and suggest that the numbers, like the famous survivor count of 2,700 out of 305,000, may have been exaggerated or refer only to particular units. The figures remain important as evidence of how contemporaries imagined the scale of the effort, even if they are not exact counts.

Why did the Sui fail? Explanations in the sources and in modern scholarship include Emperor Yang's insistence that commanders refer decisions to him, which the sources themselves blame for the failure at Liaodong; the problem of supplying huge armies over long distances in a short campaigning season between the spring thaw and the autumn rains; the strength of Goguryeo's fortress network; and divisions among the Sui commanders, visible in the quarrel between Yu Zhongwen and Yuwen Shu. Military historians such as David Graff have placed the campaigns within the broader development of large-scale warfare in medieval China, stressing logistics as much as generalship.

What were the wars about? Korean historians such as Noh Tae-don, author of the Encyclopedia of Korean Culture article, interpret them as a clash between a multipolar East Asian order, which Goguryeo sought to preserve, and the Sui ambition to build a single China-centred order. Chinese sources frame them in the language of a ruler punishing a disobedient vassal. The two views are not simply opposites: both agree that the central issue was whether Goguryeo would accept Sui supremacy.

Where was the Salsu, and how was the battle won? Most scholars identify the Salsu with the Chongchon River, which fits the distances in the sources, though other rivers have been proposed. A popular story says that Eulji Mundeok dammed the river and released the water on the Sui army as it crossed. This version was spread by Sin Chaeho and modern popular media, but no early source mentions a dam or a flood; the early texts describe an attack on the rear of an army caught half-way across.

Who was Eulji Mundeok? The Samguk sagi admits that his family origins are unknown. A late Joseon work says he came from Mount Seokda near Pyongyang, but this is not reliable. Scholars have debated whether 'Eulji' was a surname or a title, and one theory links it to the Xianbei surname Yuchi (尉遲), making him a descendant of immigrants; others see him as a member of a newly rising aristocracy from the former Lelang and Daifang region, pointing to his command of Classical Chinese. The question remains open.