Some wars spawn myths. Some spawn epics. Some spawn both; others, neither. The 13th-century Mongol invasions of Japan spawned a myth — the "divine wind" that repulsed the invading fleet — but no epic. The 12th-century Genpei War spawned an epic — the "Heike Monogatari" ("The Tale of the Heike") — but no myth.
The Genpei War was a sordid little affair — a power struggle between two rival martial clans, glorious only if death is (as it was certainly thought to be). Fighting waxed and waned. One side won, the other lost. The consequences, as it happens, were momentous. The victorious Minamoto clan launched the Kamakura Period (1185-1333) and the samurai ethos that came to define the Japanese soul. There is no telling how Japan would have evolved had the defeated Heike prevailed.
But the conflict itself, like the Trojan War with which it is often compared, is likely to strike a modern eye as kids fighting with adult weapons, killing and dying for the sheer sport and joy of it. Would it be remembered at all, if not for the magnificant "Tale of the Heike"?