Transition From Sui To Tang - Sui Campaigns Against Goguryeo and The Start of Rebellions

Sui Campaigns Against Goguryeo and The Start of Rebellions

As of 611, Sui Dynasty had just enjoyed more than two decades of peace and prosperity, as China had been united under it since it destroyed Chen Dynasty in 589, and aside from border conflicts with Eastern Tujue (which had since become a vassal state under its Qimin Khan Ashina Rangan) and Goguryeo, and one brief internal conflict between Emperor Yang of Sui, who became emperor in 604, and his brother Yang Liang the Prince of Han, the realm had not seen war. When Goguryeo's king Gao Yuan (King Yeong-yang) refused to pay homage to Emperor Yang in 610, Emperor Yang decided to plan a campaign to conquer it, and both he and the people believed that the conquest would be easy.

The logistics of staging the attack on Goguryeo, however, took much human and other tolls, as the building of a fleet and, particularly more so, the shipping of food and other supplies to the base of operations, Zhuo Commandery (涿郡, roughly modern Beijing), caused major disruptions in the farming cycle and major deaths in those conscripted to ship the supplies to Zhuo Commandery. In response, in 611, in northern China, those who were unwilling to be conscripted began to rise as agrarian rebels, led by leaders such as Wang Bo (王薄) and Liu Badao (劉霸道), and while Emperor Yang initially did not consider these rebels serious threats, the local governmental militias were unable to quell them.

Despite this, Emperor Yang launched his first campaign against Goguryeo in 612, crossing the Liao River into Goguryeo territory in spring 612. Emperor Yang personally led part of the army to put the important city Liaodong (遼東, in modern Liaoyang, Liaoning) under siege, while he sent the generals Yuwen Shu and Yu Zhongwen (于仲文) to lead the rest of the army deep into Goguryeo territory, heading toward the Goguryeo capital Pyongyang, joined by the fleet commanded by the general Lai Hu'er (來護兒). Emperor Yang, however, was never able to capture Liaodong, while Yuwen and Yu, advancing nearly to Pyongyang, were crushed by the Goguryeo general Eulji Mundeok at the Battle of Salsu and forced to withdraw with heavy losses. By fall 612, Emperor Yang was forced to terminate the campaign and withdraw as well, with only minor territorial gains. About 300,000 men had been lost in the campaign.

Not deterred, Emperor Yang launched a second campaign against Goguryeo in 613, even though the agrarian rebellions were becoming more numerous and serious. He again headed for Liaodong himself and put it under siege, while sending Yuwen and Yang Yichen toward Pyongyang. While he was sieging Liaodong, however, the general Yang Xuangan, in charge of logistics near the Sui eastern capital Luoyang, rose in rebellion, attacking Luoyang. When Emperor Yang heard the news, he withdrew his forces and sent Yuwen and Qutu Tong (屈突通) back to Luoyang ahead of himself, and Yuwen and Qutu joined with Fan Zigai (樊子蓋) and Wei Wensheng (衛文昇), the commanders of forces that Emperor Yang had left at Luoyang and Chang'an respectively, to defeat Yang Xuangan. Emperor Yang carried out heavy-handed reprisals against actual or perceived adherents of Yang Xuangan, but such actions did not deter further rebellions.

Despite this, Emperor Yang launched a third campaign against Goguryeo in 614. As Lai reached the Yalu River, however, Goguryeo submitted, sending Yang Xuangan's confederate Husi Zheng (斛斯政), who had fled to Goguryeo, back to Sui as a sign of submission. Emperor Yang terminated the campaign, but when he again summoned Gao Yuan to pay homage to him, Gao Yuan ignored his summons. Emperor Yang began to plan a fourth campaign, which, however, he was never able to launch.

Meanwhile, in fall 615, when Emperor Yang was visiting the northern city of Yanmen (雁門, in modern Xinzhou, Shanxi), Qimin Khan's son and successor Shibi Khan Ashina Duojishi, who had been displeased by Emperor Yang's attempt to keep Eastern Tujue submissive by dividing them, launched a surprise attack on Yanmen, putting it under siege. Sui forces, largely still loyal to Emperor Yang, rushed to Yanmen to try to lift the siege, and Emperor Yang himself promised great rewards for those who came to his aid. After the siege was soon lifted, however, he reneged on the promises, causing resentment among the military.