Battle of Baekgang The Battle of Baekgang , also known as Battle of Baekgang - gu or by the Japanese name Battle of Hakusukinoe ( 白村江の戦い " Hakusuki - no - e no Tatakai " or " Hakusonkō no Tatakai " ) , was a battle between Baekje restoration forces and their ally , Yamato Japan , against the allied forces of Silla and the Tang Dynasty of ancient China . The battle took place in the lower reaches of the Geum River in Jeollabuk - do province , Korea . The Silla - Tang forces won a decisive victory , forced Yamato Japan to withdraw completely from Korean affairs and crushed the Baekje restoration movement . Background . In 660 , the Korean Peninsula was divided into three kingdoms , called Baekje , Silla and Goguryeo . These three kingdoms had constantly fought with each other for control of the peninsula for several centuries up to that point . Furthermore , Goguryeo had been engaged in constant wars with the Chinese Sui and Tang dynasties in addition to the aforementioned two Korean kingdoms . While the three Korean kingdoms were not always perpetual enemies , their alliances frequently shifted ; a kingdom would become allies with one of the other two , only to later turn against that kingdom and ( sometimes ) become allies with the other kingdom against whom it had fought earlier . For instance , Silla and Baekje would be allied against Goguryeo ( as they were from the late 420 ' s to the early 550 ' s ) , and later Silla ( or Baekje ) would betray the other ( as happened in 553 , when Silla wrested control of the entire Han River basin from Baekje ) . Silla had an ongoing alliance with the Tang Dynasty dating roughly to the Tang rise to power in the 620s . The Tang made a series of assaults against Goguryeo , but were never able to conquer it . All the Tang invasions had been from the north attacking the south . Tang decided that the best strategy might be to attack Goguryeo from both the northern front and a southern front simultaneously with their ally Silla . However , in order to do this , they ( Tang and Silla ) had to eliminate Goguryeo ' s nominal ally Baekje and secure a base of operations in southern Korea for a second front . Together , Silla and Tang invaded Baekje and effectively eliminated it when they captured the capital of Sabi , as well as Baekje ' s last king , Uija , and most of the royal family . Soon afterwards , however , the Baekje people revolted and threw off Silla and Tang rule in large areas of northern Baekje . The Baekje general Boksin attempted to take back the 40 lost counties . He also recalled Prince Buyeo Pung from Japan , sent 100 Tang prisoners to the Yamato court and requested military aid . General Boksin proclaimed Prince Buyeo Pung as the new king of 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 surroundings . 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 and their royal houses had blood relations . Japanese relationship with the Baekje ( Kudara ) kingdom in southwest Korea was very close , and it is possible that both ruling families were related in some way . The fall of Baekje in 660 came as a terrible shock to the Yamato royal court . Empress Saimei had 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 Baekje restoration forces . The troops were drawn from local strongmen ( " kuni no miyatsuko " ) from mostly western Honshū , Shikoku , and especially from Kyūshū , though 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 tanka : The Empress died in Tsukushi shortly after the last waves of Yamato troops departed for Korea . The Crown Prince ( Tenji ) carried her remains back to Asuka . Tenji , dressed in white mourning clothes , set up his residence in the Nagatsu temporary palace in Kyūshū , and continued to oversee the expeditionary operation . Around August 661 , 5 , 000 soldiers , 170 ships , and the general Abe no Hirafu , arrived in Baekje restoration controlled territory . 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 August 27 , 663 , the advance guard of the Japanese fleet tried to force their way , but Tang ships held firm , repelled the attacks and maintained disciplined ranks . On 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 . Chinese sources claim 10 , 000 Japanese deaths . Silla participation in the battle involved cavalry forces that defeated Baekje restoration ground troops that were supporting the Yamato navy on the banks of the river . It is unclear as to whether or not this took place before the Japanese navy went to battle Tang ships or during . Without Yamato troops to lift the siege , the fortress of Churyu surrendered to Silla and Tang forces on September 7 , 663 . Buyeo Pung took a boat and fled with several followers to Goguryeo . 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 .