Haedong Myeongjangjeon, known as the "Biographies of Famed Korean Generals", written in the 18th century, states that he was from Seokda Mountain (石多山) near Pyongyang.

In 589, the Sui dynasty conquered several surrounding states and launched several large military campaigns against Goguryeo, which was unwilling to submit to its dominance.

The Sui army quickly overran Goguryeo's border defenses, then camped on the banks of the Liao River and prepared to bridge it.

He prepared his troops to meet the numerically superior Sui forces with a strategy of deception, using feigned retreats and sudden attacks.

When the rains stopped, Emperor Yang 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 Mundeok drew the Sui forces further and further from their supply centers.

[6] The Sui dynasty was beginning to disintegrate and Emperor Yang decided that he urgently needed to expand his empire in order to regain power, but two more attacks on Goguryeo in the following spring were met with similar disasters, and eventually internal rebellion in China forced him to abandon his desire for Goguryeo.

Field Marshal Eulji Mundeok's strategy and leadership had protected Goguryeo from Chinese expansion into the Korean peninsula.

One of the most distinguished military leaders of the Goguryeo period, Eulji Mundeok's leadership and tactical acumen were the decisive factors in defeating the Sui invasion.

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.

UFG is the world's largest computerized command and control exercise, focusing on how US and ROK forces would defend against a North Korean attack.