Eulji Mundeok Eulji Mundeok ( or Ulchi Mundok , McCune – Reischauer romanization ) was a military leader of early 7th century Goguryeo , one of the Three Kingdoms of Korea , who successfully defended Goguryeo against the Sui Chinese . He is often numbered among the greatest heroes in Korean military history . Background . Eulji was born in the mid - 6th century and died sometime after 618 , although the exact date is unknown . " Haedong myeongjangjeon " ( Biographies of famed Korean Generals ) , written in 18th century Joseon , states that he was from the Mountain Seokda ( 石多山 ) in Pyongyang . At the time of his birth , the kingdom of Goguryeo had grown to be a powerful and belligerent state , constantly warring with its neighbours , Chinese states to its north and west , and its fellow Korean kingdoms Silla and Baekje to its southeast and southwest respectively . A balance of power was maintained between these Three Kingdoms of Korea , until outside influence , namely the much larger Tang Dynasty of China , finally tipped the advantage to Silla . In 589 , the Sui Dynasty had reunified China for the first time since the fall of the Han Dynasty over three centuries before . The Sui early on launched several large military campaigns against Goguryeo which was unwilling to submit to Sui dominance . Eulji Mundeok ( Some Korean scholars posit that the Eulji 乙支 in his name is some form of Goguryeo rank or title ) was an educated man , skilled in both " mun " ( 문 , 文 ) political and the " mu " ( 무 , 武 ) military science s . He eventually rose to become Prime Minister of Goguryeo . The Battle of Salsu River . After the founding of the Sui dynasty in 589 , a precarious peace obtained for several years between the new Chinese dynasty and Goguryeo . In 597 , however , the Goguryeo King Yeongyang launched raids across the Liao River , which is the traditional border with China . In response , the Sui invaded Goguryeo , but the invasion failed as the invasion force was scattered by a typhoon . In the early 7th century , however , the new Sui emperor Yangdi learned of secret Goguryeo correspondence with the Eastern Turkish khanate . Yangdi took a hard stand and demanded the King Yeongyang come and submit personally to Sui or face an " imperial tour of his territories " . When the King Yeongyang failed to submit in this fashion , Yangdi prepared for war . He mustered an army of over 1 , 133 , 800 troops and more than 2 million auxiliaries and personally led them against Goguryeo in 612 . They quickly overran Goguryeo ' s border defenses , camped on the banks of the Liao River and prepared to bridge it . Eulji Mundeok , commissioned as a Field Marshal , was called upon to assist in the defence of the nation , and prepared his troops to meet the superior Sui forces with a strategy of false retreat , deception and attack . After the Sui forces crossed the Liao River , a small contingent was sent to attack the Goguryeo city of Yodong , but Field Marshal Eulji sent Admiral Gang Yi - sik and his forces to meet them there and drove them out . As the rainy season progressed , the Sui forces launched other small probing attacks , but held off from making any large moves before the end of the rainy season . When the rains stopped , Yangdi moved his forces to the banks of the Yalu River in northwestern Korea and prepared for a major battle . Fighting only small engagements at times and places of his choosing , Eulji drew the Sui forces further and further from their supply centers . A Sui advance force of over 305 , 000 men was sent to take the city of Pyongyang . After allowing the force to approach the city , Field Marshal Eulji ambushed it . His forces attacked from all sides , driving the Sui troops back in utter confusion . His troops pursued the retreating army , slaughtering them at will ; records claim that only 2 , 700 men of the massive force returned alive to the main Chinese army . This battle , the Battle of Salsu , came to be known as one of the most glorious military triumphs in Korea ' s national history . ( It was said that Eulji had built a large dam upon the Salsu river which made the waterbed shallow , and as the Sui troops crossed the dam was broken down , releasing a huge current of water upon the unsuspecting troops , thus wiping out nearly the entire fleet with one blow ) . After the battle , winter began to set in and the Sui forces , short on provisions , were forced to return home . Death . Eulji Mundeok managed to protect Sin Fortress from a Sui invasion force , but he died not long after . The Sui Dynasty was beginning to disintegrate and Yangdi decided that he urgently needed to expand his empire in order to regain power , but two more attacks on Goguryeo by Yangdi the following spring met with similar disaster , and eventually internal rebellion in China forced the Sui to abandon their desire for Goguryeo . By 618 , the relatively short - lived Sui Dynasty was replaced by the Tang Dynasty . Field Marshal Eulji Mundeok ' s strategy and leadership had protected Goguryeo from the Chinese expansion to the Korean peninsula . Legacy . One of the most distinguished military leaders of the Goguryeo period , Eulji ' s leadership and tactical acumen was the decisive factor in defeating the Sui invasion . Facing vastly numerically superior forces , he developed a strategy that allowed him to secure a decisive victory . Such spectacular tactical success was sufficient to earn him a permanent place among Korea ' s most famous leaders . Kim Bu - sik , the author of the Samguk Sagi , also attributed the outstanding victory over Sui to the Eulji ' s great deed . In Korea , Eulji Mundeok has been recognized as one of the greatest figures in its national history . During the reign of Hyeonjong in the Goryeo period , a shrine of Eulji Mundeok was built near Pyongyang . In the succeeding Joseon period , he remained just as revered a figure . Yang Seong - ji , a scholar and high - ranking bureaucrat of the Early Joseon , and An Jeong - bok , a Silhak historian of Late Joseon , both thought highly of him . Furthermore , King Sukjong of Joseon ordered the construction of another shrine in honour of Eulji Mundeok in 1680 . At a time when Korea was suffering under the yoke of Japanese Imperialism , a fuller assessment of Eulji commenced with the Korean historian Shin Chaeho ( 신채호 , 申采浩 , 1880 – 1936 ) , who published a biography of Eulji in 1908 and held him out as an example of Korea ' s traditional nationalist spirit . Eulji Mundeok is still celebrated as a great Korean hero . One of the most preeminent Korean scholars of the 20th century , Lee Ki - baik , noted that Eulji ' s efforts in halting the Sui attempt at conquest stand as one of the earliest examples of Korean attempts to fend off foreign domination . Today a main thoroughfare in downtown Seoul , Euljiro , is named after Eulji Mundeok . The second highest Military Decoration of South Korea , Field Marshal Lord Eulji ' s Order of Military Merit , is also named in his honour . Eulji Mundeok ' s literary work , the Eulji Mundeok Hansi , is one of the oldest surviving poems in Korean literature . One of the biannual Combined Forces Command exercises between South Korea and the United States was called Ulchi - Focus Lens ( UFL ) in honor of Eulji Mundeok . It has now been renamed Ulchi - Freedom Guardian ( UFG ) . UFG is the world ' s largest computerized command and control exercises , focusing on how U . S . and South Korean forces would defend against a North Korean attack .