Rain bangs the oars as a Baekje prince, 부여풍, begs in a shrine yard for ships. Across the water a Japanese envoy thinks of the carpenters and monks his court borrowed from Baekje for decades.
Baekje (백제) had been Japan's teacher for years. Craftsmen, monks, and scribes from Baekje had rebuilt temples, taught sutras, and fixed ships at the Yamato court. That made Baekje feel like family to many in Japan, and it meant Japan had skin in any fight on the peninsula.
After Baekje fell in 660, a ragged restoration group led by 복신 and the prince 부여풍 begged for help. Japan answered with a big fleet, several hundred ships and several thousand men by the common counts, and in 663 they met Tang and Silla forces at Baekgang (백강). The allied Baekje-Japanese fleet was smashed, many ships burned, and survivors were captured or thrown ashore. The defeat ended any chance of a Baekje comeback.
The shock changed East Asia. Japan stopped sending big expeditionary forces and poured money into home defenses, stone walls, and new naval yards. Silla used Tang help to finish off its rivals, then had to push Tang troops back later to keep Korean independence. Baekje’s people scattered, but their artisans and ideas kept reshaping Japan for generations.
Alliances can drag friends into fights across oceans, and help can erase the state you meant to save. Send this to someone who thinks foreign aid is only spreadsheets and good vibes.