Battle of Baekgang - Aftermath

Aftermath

The Battle of Baekgang was Japan's greatest defeat in its premodern history. Japan's losses were enormous and there would be no state-sponsored troop deployments to Korea for over 900 years (until Hideyoshi's invasions of Korea in the late 16th century). Japan also lost a key ally on the East Asian continent in Baekje as well as a direct link to continental technology and culture. Due to the scale and severity of their defeat, the Yamato court would fear an invasion from Tang or Silla or both and built a huge network of shore fortifications throughout the rest of the 600's. In 664, the Yamato court established frontier guards and signal fires in Tsushima Island, Iki Island, and northern Kyushu. Also embankments storing water were built around the fortresses in Kyushu which were called the Water Fortress. In 665, the Yamato court sent Baekje generals and artisans to construct a rampart in Nagato province, and two ramparts in Kyūshū. In 667, a rampart was constructed in the Yamato region, another one at Sanuki, and yet another at Tsushima island. The Japanese would continue to build fortifications until 701; whether this was due to the diversion of royal funds to more pressing priorities or a realization that Silla had no designs on Yamato territory is unclear.

For Baekje, the battle was the knockout blow that ended any hope of reviving the kingdom. Many Baekje people defected to either Goguryeo or Japan. Baekje royalty who fled to Japan were given the same ranks and titles in the Yamato court and Baekje refugees were given de facto citizenship status or special artisan status.

The victory gave Tang control of all former Baekje lands in Korea and a secure base in southwest Korea to launch a two-pronged invasion of Goguryeo with their ally Silla. The Silla-Tang alliance first launched attacks on Goguryeo from the south in 661 and the Goguryeo capital at Pyongyang finally fell in 668. In the same year, Tang established the Protectorate General to Pacify the East to control the Korean Peninsula.

The battle also introduces interesting questions regarding Japan's relations with the Korean states and their level of development at the time. For example—why did the Japanese fare so badly against the Tang army? According to several scholars, it is clear that in the 7th century, the Chinese had better weapons and more importantly, their troops and officers were better trained and disciplined. Despite years of reforms modeled after mainland examples from China, the Yamato armies did not adopt the organized infantry tactics of Chinese armies. Furthermore, Yamato Japan was still a nascent and developing state run in practice by local strongmen (though in theory by the royal court) and without any real form of unified command. In addition, Japanese soldiers were drawn from many corners by local "strongmen" that controlled their own territories. It is also doubtful that, among the Japanese, there was much standardization in either weapons or unit tactics.

Another interesting question that has puzzled many scholars is—why did Yamato go through so much effort to protect Baekje? Bruce Batten sums it up by saying:

"Why the Japanese should have thrown themselves with such vigor into a war that, if not quite an intramural Korean conflict, had at least no direct bearing on Japanese territory, is not easy to answer."

The battle, as well as all the preparation behind it, shows clearly (aside from any other documentation) that there were strong ties between Yamato Japan and Baekje of Korea that might have been beyond the obvious military, political and economic interests that are regularly shared between states. The linguist J. Marshall Unger suggests, based on linguistic evidence, that Baekje may represent a remnant proto-Japanese or para-Japanese community which stayed behind on the Korean peninsula after the Yayoi migrations but still maintained a conscious connection to the Yayoi people and their descendants. In any case, the phenomenon of elite refugees fleeing political conflict on the peninsula and settling in Yamato had been recurring in waves since at least the 5th century.