Battle of Salsu
The Battle of Salsu was a major battle that occurred in the year 612 during the second campaign of the Goguryeo–Sui War between Goguryeo of Korea and Sui of China. Goguryeo won an overwhelming victory over the numerically superior Sui forces at Salsu River.
History
In 612, Emperor Yang of Sui invaded Goguryeo with 1,138,000 men. Unable to overcome the stalwart Goguryeo defense at Yodong Fortress and other fortifications in Liaodong, he dispatched 300,000 troops to directly take Pyongyang, the capital of Goguryeo.The Sui forces labored in their advance to the Goguryeo capital, due to the internal discord within the Sui military command and a poor supply line. Troops had been given a large amount of supplies which were expected to last the entire march, a heavy burden which ended up being abandoned by exhausted troops en route. Goguryeo General Ŭlchi Mundŏk gauged the morale and exhaustion of the Sui army by feigning surrender and touring the Sui camp. Although the Sui commander Yu Zhongwen had been instructed by Emperor Yang to capture Ŭlchi Mundŏk upon encounter, another general, Liu Shilong, recommended Ŭlchi's release to negotiate surrender terms with the Goguryeo King Yeongyang. After his successful escape and fully aware of the Sui army's turmoil, Ŭlchi lured the Sui troops deep into Goguryeo territory, furthering the Sui troops' exhaustion and worsening morale.
Although the Sui army approached Pyongyang, troops were in no condition to besiege the fortified capital without any further supplies. The army expected to be supplied upon arrival at Pyongyang by a naval force commanded by Lai Hu'er, but they had been already defeated by Goguryeo troops in an ambush within Pyongyang by Go Geonmu, the King's younger half-brother. Realizing their situation and goaded by Ŭlchi's poem encouraging retreat, the Sui commanders decided to retreat back to Liaodong. Goguryeo forces then pursued the retreating Sui forces in a series of attacks, culminating in a climactic battle at Salsu, where pursuing Goguryeo troops cut down vulnerable Sui troops crossing the river Chongchon. Korean nationalist historian Sin Chaeho and modern popular portrayals float the idea of Ŭlchi using a dam to inflict damage on the Sui army, but no contemporaneous source attests to the use of a dam or a water attack.
The surviving Sui troops were forced to retreat at a breakneck pace to the Liaodong Peninsula to avoid being killed or captured. Many retreating soldiers died of disease or starvation as their army had exhausted their food supplies. This led to an overall campaign loss of all but 2,700 Sui troops out of 305,000 men. The Battle of Salsu is listed among the most lethal "classical formation" battles in world history.