The Goguryeo-Sui War, spanning from CE 598 - 614, was a series of military invasions initiated by the Sui Dynasty of China against Goguryeo, one of the Three Kingdoms of Korea. Under the leadership of Emperor Wen and later his successor, Emperor Yang, the Sui Dynasty aimed to subdue Goguryeo and assert its dominance in the region. Goguryeo, led by King Pyeongwon followed by King Yeongyang, resisted these efforts, insisting on maintaining an equal relationship with the Sui Dynasty. Initial attempts to subdue Goguryeo were met with strong resistance, including an early setback in 598 due to unfavorable weather conditions and fierce Goguryeo defense, resulting in heavy Sui losses.

The most significant campaign occurred in 612, with Emperor Yang mobilizing a massive army, reportedly over a million strong, to conquer Goguryeo. The campaign involved prolonged sieges and battles, with Goguryeo employing strategic retreats and guerrilla tactics under the command of General Eulji Mundeok. Despite initial successes in crossing the Liao River and advancing towards Goguryeo territories, the Sui forces were ultimately decimated, most notably at the Battle of Salsu River, where Goguryeo forces ambushed and inflicted severe casualties on the Sui army. Subsequent invasions in 613 and 614 saw similar patterns of Sui aggression met with staunch Goguryeo defense, leading to further Sui failures.

The Goguryeo-Sui Wars played a pivotal role in weakening the Sui Dynasty, both militarily and economically, contributing to its eventual collapse in 618 and the rise of the Tang Dynasty. The massive loss of life, depletion of resources, and loss of trust in the Sui governance fueled widespread discontent and rebellion across China. Despite the enormous scale of the invasions and the initial might of the Sui forces, Goguryeo’s resilience and strategic acumen under leaders like King Yeongyang and General Eulji Mundeok enabled them to withstand the onslaught and protect their sovereignty, marking the wars as a notable chapter in Korean history.