Baekje – Tang War The Baekje – Tang War was fought between the Tang and Baekje between 660 and 663 . After numerous attacks by Baekje and Goguryeo , King Muyeol of Silla sought help from Emperor Gaozong of Tang to defend his exhausted kingdom against the attacks . Emperor Gaozong received and granted his request . In 660 , he launched the invasion of Baekje . Background . The Silla kingdom had formed a military alliance with the Tang empire under Emperor Gaozong ' s reign . When Goguryeo and Baekje attacked Silla from the north and west respectively , Queen Seondeok of Silla had sent an emissary to the Tang empire to desperately request military assistance . In 650 , Emperor Gaozong received a poem , written by Queen Seondeok , from the princely emissary Kim Chunchu ( who would later accede the Silla throne as King Muyeol ) . Baekje had allied with Yamato Wa in 653 . Even though Baekje was allied with Goguryeo , the Han River valley separated the two states and was a hindrance in coming to each other ' s aid in time of war . King Muyeol assumed the Silla throne in 654 . Between 655 and 659 , the border of Silla was harassed by Baekje and Goguryeo ; Silla therefore requested assistance from Tang . Course . In 658 , Emperor Gaozong had sent an army to attack Goguryeo . Shortly afterwards , in 660 , he sent an army of 130 , 000 troops towards Baekje to further relieve Silla . During this expedition , Admiral Su Dingfang commanded the Tang fleet and sailed it straight towards Baekje . The Tang fleet sailed across the Yellow Sea , towards Geum River , and landed its army on the western coastline of Baekje . After the landing of the army , the 130 , 000 Tang troops marched further towards Sabi , the capital of Baekje . Crown Prince Kim Beopmin , General Kim Yusin , General Kim Pumil , and General Kim Heumsun were dispatched to command 50 , 000 Silla troops and set off westwards into the Battle of Hwangsanbeol . The Silla forces marched into Baekje from the eastern border , and crossed through Sobaek Mountains . General Kim Yusin led the Silla army across the passes of Tanhyon towards Hwangsan Plain . General Gyebaek could only assemble a force of about 5000 Baekje troops in defense against the advancing front of the Silla army . At Hwangsan Plain , the Silla army defeated the Baekje forces of General Gyebaek . In 660 , the Baekje capital Sabi fell to the forces of Tang and Silla . Around 10 , 000 Baekje troops were killed in the siege . Baekje was conquered in 18 July 660 , when King Uija of Baekje surrendered at Ungjin . The Tang army took the king , crown prince , 93 officials , and 20 , 000 troops as prisoner . The king and crown prince were sent as hostages to the Tang empire . The Tang empire annexed the territory and established five military administrations to control the region instead of Silla , which they painfully accepted . Aftermath . In a final effort , General Gwisil Boksin led the resistance against Tang occupation of Baekje . He requested military assistance from their Yamato allies . In 661 , Empress Saimei ( also reigned as Empress Kōgyoku ) and Prince Naka no Ōe prepared for battle and sent Prince Buyeo Pung of Baekje , who had been in Yamato Wa for over 30 years , to aid the resistance . In 662 , they sent an expedition to assist General Gwisil Boksin . A year later , 27 , 000 Yamato troops were sent as reinforcement . The Tang fleet , comprising 170 ships , advanced towards Chuyu and encircled the city at Baekgang River . As the Yamato fleet engaged the Tang fleet , they were attacked upon by the Tang fleet and were destroyed . In 663 , the Baekje resistance and Yamato forces were annihilated by the Tang and Silla forces at the Battle of Baekgang . During the engagement , General Echi no Takutsu was slayed . Subsequently , Prince Buyeo Pung of Baekje and few of his men fled to Goguryeo .