Battle of Baekgang

The Battle of Baekgang or Battle of Baekgang-gu, also known as Battle of Hakusukinoe (白村江の戦い) in Japan, as Battle of Baijiangkou in China, was a battle between Baekje restoration forces and their ally, Yamato Japan, against the allied forces of Silla and Tang China. The battle took place in the Baengma River or Baek River, which is the lower reach of the Geum River in Jeollabuk-do province, Korea. The Silla-Tang forces won a decisive victory, compelling Yamato Japan to withdraw completely from Korean affairs and crushing the Baekje restoration movement.

Background
In the first half of the first millennium CE, the Korean Peninsula was divided into three kingdoms – Baekje, Silla, and Goguryeo. These three kingdoms were rivals, and had engaged each other in wars for dominion over the peninsula for several centuries. In addition to the inter-Korean rivalry, Goguryeo had been engaged in frequent warfare with the Chinese Sui and Tang dynasties. While the three Korean kingdoms were not always military enemies, their alliances frequently shifted. For example, Silla and Baekje were allied against Goguryeo from the late 420s to the early 550s. Later in 553, Silla betrayed its former ally and wrested control of the entire Han River basin from Baekje. Although the restoration forces had some initial success against Tang and Silla troops, by 662, they were in serious trouble, and their area of control was confined to the fortress of Churyu and its immediate vicinity. As their situation went from bad to worse, Buyeo Pung had Boksin killed for fear of insurrection.

Baekje and Yamato Japan had been long-standing allies by this time, and their royal houses were related, so Baekje royals resided in Japan throughout the centuries as a token of goodwill to ask for favors from Japan, but also acting as spies. (But only when Baekje was eliminated were Princes Buyeo Pung and his brother, and no other Baekje royal prior, came to be listed in the Nihon Shoki as "hostages." "Hostage" practices like this would continue all the way to early modern Japan when Toyotomi Hideyoshi would send his mother Ōmandokoro and half-sister Asahihime to the lesser warlord Tokugawa Ieyasu to bargain for Ieyasu's surrender. Of note, there have also been cases of Nihon Shoki deliberately recording visiting foreign diplomats as "hostages" such as King Muyeol of Silla who entered and left Japan for a diplomatic mission with China without being waylain, in but a span of few months). The fall of Baekje in 660 came as a terrible shock to the Yamato royal court. Empress Saimei said: "We learn that in ancient times there have been cases of troops being asked for and assistance requested: to render help in emergencies, and to restore that which has been interrupted, is a manifestation of ordinary principles of right. The Land of Baekje, in its extremity, has come to us and placed itself in our hands. Our resolution in this matter is unshakable. We will give separate orders to our generals to advance at the same time by a hundred routes."

Crown Prince Naka no Ōe, later to become Emperor Tenji, and Empress Saimei decided to dispatch an expeditionary force led by Abe no Hirafu (阿倍比羅夫) to help the besieged Baekje restoration forces. The troops were largely local strongmen (kuni no miyatsuko) drawn from mostly western Honshū, Shikoku, and especially Kyūshū, although some warriors were also from Kantō and northeastern Japan.

Empress Saimei moved the capital to the Asakura temporary palace near the shipyards in northern Kyūshū to personally oversee the military campaign. As the main fleet set sail, the Man'yōshū records Empress Saimei composing a waka:


 * 熟田津に 船乗りせむと 月待てば 潮もかなひぬ 今は漕ぎ出でな
 * Nikita tsu ni funanori semu to tsuki mateba, shio mo kanahinu: ima ha kogiide na.
 * I was going to wait for the moon to rise before embarking from Nikita bay, but the tide is up: go, row out now!

Around August 661, 5,000 soldiers, 170 ships, and the general Abe no Hirafu all arrived in territory controlled by the Baekje restoration forces. Additional Japanese reinforcements, including 27,000 soldiers led by Kamitsukeno no Kimi Wakako (上毛野君稚子) and 10,000 soldiers led by Iohara no Kimi (廬原君), arrived in 662.

The battle
In 663, Baekje restoration forces and the Yamato navy convened in southern Baekje with the intent to relieve the capital of the Baekje restoration movement in Churyu, which was under siege by Silla forces. The Yamato navy was to ferry ground troops to Churyu via the Geum River and lift the siege. However, Tang also sent 7,000 soldiers and 170 ships to blockade Yamato reinforcements from relieving the capital.

On 4 October 663 (27 August by the lunar calendar), the advance guard of the Japanese fleet tried to force their way, but using common doctrine and strong formation, the Tang ships held firm, repelling the attacks and displaying greater tactical sophistication than the Japanese fleet.

On 5 October 663 (28 August by the lunar calendar), the second day of the battle, the arrival of Japanese reinforcements made their forces several times larger than the Tang fleet arrayed against them. However, the river was narrow enough where the Tang fleet could cover their front and protect their flanks as long as they maintained their ordered battle lines. The Japanese were confident in their numerical superiority and attacked the Tang fleet at least three times throughout the entire day, but the Tang fought off each attack. Towards the end of the day, the Japanese became exhausted, and their fleet lost cohesion through their repeated attempts to break through Tang lines. Sensing the right moment, the Tang fleet moved reserves and counterattacked, breaking both the left and right flanks of the Japanese, enveloping their fleet and crowding in the ships so they could not move or retreat. Many Japanese fell into the water and drowned, and many of their ships were burned and sunk. The Yamato general Echi no Takutsu was killed after striking down more than a dozen men in close quarters combat.

Japanese, Korean, and Chinese sources all point to heavy Japanese casualties. According to the Nihon Shoki, 400 Japanese ships were lost in the battle.

Retrospective issues
Many scholars have also puzzled over why Yamato went through so much effort to protect Baekje. Bruce Batten summarized:

"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, clearly illustrates (aside from any other documentation) the strong ties between Yamato Japan and Baekje of Korea transcending the usual interstate military, political, or economic interests. The linguist J. Marshall Unger suggests, based on linguistic evidence, that Baekje could represent a remnant proto-Japanese or para-Japanese community, which had 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.