The name "Genpei" (sometimes romanized as Gempei) comes from alternate readings of the kanji "Minamoto" (源 Gen) and "Taira" (平 Hei, pronounced as the second element in some compounds as -pei).

The Genpei War was the culmination of a decades-long conflict between the two aforementioned clans over dominance of the Imperial court and, by extension, control of Japan.

[6] In June 1180, Kiyomori moved the seat of imperial power to Fukuhara-kyō, "his immediate objective seems to have been to get the royal family under his close charge.

[6]: 289  However, he successfully made it to the provinces of Kai and Kōzuke, where the Takeda and other friendly families helped repel the Taira army.

"[6]: 292 Taira no Kiyomori died from illness in the spring of 1181, and around the same time Japan began to suffer from a famine which was to last through the following year.

Taira no Munemori, head of the clan since his father Kiyomori's death, led his army, along with the young Emperor Antoku and the Imperial regalia, to the west.

[6]: 293–294 In 1183, Yoshinaka once again sought to gain control of the Minamoto clan by planning an attack on Yoritomo, while simultaneously pursuing the Taira westward.

Betrayed by Yukiie, Yoshinaka took command of Kyoto and, at the beginning of 1184, set fire to the Hōjūjidono, taking the Emperor into custody.

[6]: 296–297 As the united Minamoto forces left Kyoto, the Taira began consolidating their position at a number of sites in and around the Inland Sea, which was their ancestral home territory.

They received a number of missives from the Emperor offering that if they surrendered by the seventh day of the second month, the Minamoto could be persuaded to agree to a truce.

[6]: 297 The Minamoto army, led by Yoshitsune and Noriyori, made their first major assault at Ichi-no-Tani, one of the primary Taira camps on Honshū.

Though on the retreat, the Taira enjoyed the distinct advantages of being in friendly, home territories, and of being far more adept at naval combat than their rivals.

The Minamoto engaged the Taira fleet in the Straits of Shimonoseki, a tiny body of water separating the islands of Honshū and Kyūshū.

The tides played a powerful role in the development of the battle, granting the advantage first to the Taira, who were more experienced and abler sailors, and later to the Minamoto.

][12] as it completed Yoritomo's nationwide domination through the annexation of Dewa and Mutsu Province, and that its end marked the establishment of the first military government, the Kamakura shogunate.

[14] Furthermore, the Battle of Ōshū was fought between Minamoto no Yoritomo and his last strong enemy, the Northern Fujiwara, years after the Taira clan had been destroyed.

Following the call to arms of Prince Mochihito and Minamoto no Yorimasa in 1180, the clan would gather together and rise to power again.

The novel Shike by Robert Shea features a somewhat fictionalized account of the wars, as seen from the perspectives of his two main characters, the Zinja Monk Jebu, and the Noblewoman Lady Shima Taniko.

Another fictionalized account of the conflict forms the central plot of "Civil War" (also known as "Turbulent Times"), the ninth volume of Osamu Tezuka's celebrated Phoenix series of comics.