Goguryeo-Sui War

Goguryeo–Sui War
Date 598, 612 – 614 Location Manchuria, Northern Korean Peninsula, Yellow Sea Result Goguryeo victory One of the major causes of the fall of the Sui Dynasty
Belligerents
Goguryeo	Sui Dynasty
Commanders and leaders
King Yeongyang Eulji Mundeok Go Geon-mu Gang Yi-sik (?)	Yang Liang Gao Jiong Emperor Yang of Sui Yuwen Shu Yu Zhongwen Lai Hu'er Zhou Luohou
Strength
Unknown	Allegedly 1,133,000 troops during the second invasion of 612 in the Book of Sui. However, the strength and losses were inflated by Tang historians to discredit the preceding Sui. Modern estimates are closer to ~600,000 .
Casualties and losses
Unknown	Unknown

Goguryeo victory

Allegedly 1,133,000 troops during the second invasion of 612 in the Book of Sui.
However, the strength and losses were inflated by Tang historians to discredit the preceding Sui.
Modern estimates are closer to ~600,000

The Goguryeo–Sui War were a series of campaigns 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.

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.

Wendi of Sui was displeased with the challenge from Goguryeo, which continued small scale raiding into Sui's northern border. Wendi 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.

...
Wikipedia