A History of Japan: From Mythology to Nationhood/The Late Heian Period

The Heian Period ends with the Genpei War (源平合戦), fought between the Minamoto (源) and the Taira (平) clans. It occurs during the Late-Heian Period and marks the rise of the military class, and the formation of the Kamakura Shogunate under Minamoto Yoritomo.

Background
The Genpei War was the culmination of a decades-long conflict between the two clans over dominance of the Imperial court and control of Japan. In the Hōgen Rebellion and in the Heiji Rebellion of earlier decades, the Minamoto attempted to regain control from the Taira and failed. The Taira then began a series of executions, intended to eliminate their rivals.

In 1177, relations between the Taira clan and the retired Emperor Go-Shirakawa became highly strained, and the latter attempted a coup d'état to oust the Daijō Daijin (prime minister), Taira no Kiyomori. Kiyomori defeated the former emperor and abolished the Insei system. This provoked strong anti-Taira sentiment.

On March 21, 1180, Taira no Kiyomori put his grandson, Antoku (then only two years of age), on the throne, after the abdication of Emperor Takakura. Go-Shirakawa's son, Prince Mochihito, felt that he was being denied his rightful place on the throne and, with the help of Minamoto Yoritomo, sent out a call to arms to the various samurai families and Buddhist monasteries on May 5. In June, Kiyomori moved the seat of imperial power to Fukuhara (modern day Kobe), in the hope of promoting trade with Song Dynasty China, and on the fifteenth of that month, Prince Mochihito fled Kyoto to take refuge in Mii-dera.

Beginnings of the War
The actions of Taira no Kiyomori having deepened Minamoto hatred for the Taira clan, a call for arms was sent up by Minamoto no Yorimasa and Prince Mochihito. Not knowing who was behind this rally, Kiyomori called for the arrest of Mochihito, who sought protection at the temple of Mii-dera. The Mii-dera monks were unable to ensure him sufficient protection, so he was forced to move along. He was then chased by Taira forces to the Byōdō-in, just outside Kyoto. The war began thus, with a dramatic encounter on and around the bridge over the River Uji. This battle ended in Yorimasa's ritual suicide inside the Byōdō-in and Mochihito's capture and execution shortly afterwards.

It was at this point that Minamoto no Yoritomo took over leadership of the Minamoto clan and began traveling the country seeking to rendezvous with allies. Leaving Izu Province, heading for the Hakone Pass, he was defeated by the Taira in the battle of Ishibashiyama. However he successfully made it to the provinces of Kai and Kozuke, where the Takeda and other friendly families helped repel the Taira army. Meanwhile, Taira no Kiyomori, seeking vengeance against the Mii-dera monks and others, besieged Nara and burnt much of the city to the ground.

Fighting continued the following year. Minamoto no Yukiie launched an unsuccessful sneak attack attempt against the army of Taira no Tomomori at the Battle of Sunomatagawa. He was pursued by them to the Yahahigawa, destroying the bridge over the river in order to slow the Taira progress. He was defeated and forced to withdraw once again, but Taira no Tomomori fell ill and called off his pursuit of Yukiie's forces.

Taira no Kiyomori died from illness in the spring of 1181, and around the same time Japan began to suffer from a famine which would last through the following year. The Taira moved to attack Minamoto no Yoshinaka, a cousin of Yoritomo, who had raised forces in the north but were unsuccessful. For nearly two years, the war ceased, only to resume in the spring of 1183.

Turning of the tide
Minamoto no Yoritomo, suspicious of the strength of his cousin, launched a series of attacks against Yoshinaka. Yoshinaka had sought to take for himself lands controlled by Yoritomo, which had earlier belonged to Yoshinaka's father. Though the two reconciled with one another and agreed to focus on their common enemy, the Taira, this rivalry would remain strong throughout the war. Forced to recognize Yoritomo as the head of the clan and to send his son Yoshitaka to Kamakura as a hostage, Yoshinaka would not truly fight alongside his cousin for much of the war. He sought to defeat the Taira himself and to reach Kyoto before Yoritomo, claiming victory and the according honor and power.

Placating Yoritomo's suspicions of treachery or betrayal, Yoshinaka survived an assault on his fortress at Hiuchiyama by Taira no Koremori and engaged Koremori again at the battle of Kurikara. Yoshinaka's victory for the Minamoto at Kurikara, also known as the battle of Tonamiyama, would prove to be the turning point in the war. Through creative tactics, skillful division of his forces and a series of bluffs and diversions, Yoshinaka inflicted heavy losses on the Taira, who fled, confused and demoralized.

The Taira loss at Kurikara was so severe that they found themselves, several months later, under siege in Kyoto, with Yoshinaka approaching the city from the northeast and Yukiie from the east. Both Minamoto leaders had seen little or no opposition in marching to the capital and now forced the Taira to flee the city. 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 his clan's fortresses in western Honshū and Shikoku.

Internal Minamoto clan hostilities
The Taira clan set fire to their Rokuhara palace and the surrounding district, leaving Minamoto no Yoshinaka with the only force of any significant power in the Home Provinces surrounding the capital. Empowered with a mandate by Emperor Go-Shirakawa to pursue the Taira and destroy them, Yoshinaka once again sought to gain control of the Minamoto clan and regain his ancestral lands from his cousins Yoritomo and Yoshitsune.

Meanwhile, the fleeing Taira set up a temporary Court at Dazaifu in Kyūshū, the southernmost of Japan's main islands. They were forced out soon afterwards by local revolts, spurred by Emperor Go-Shirakawa and sought refuge at Yashima, a small island in the Inland Sea.

Yoshinaka sent a force to pursue the Taira, while he led a second force back to Kamakura to delay his cousins' actions. While his men lost to the Taira at Mizushima, Yoshinaka conspired with Yukiie to seize the capital and the Emperor, possibly even establishing a new Court in the north. However, Yukiie revealed these plans to the Emperor, who communicated them to Yoritomo. Betrayed by Yukiie, Yoshinaka took command of Kyoto and, at the beginning of 1184, set fire to the Hōjūjidono, taking the Emperor into custody. Minamoto no Yoshitsune arrived soon afterwards with his brother Noriyori and a considerable force, driving Yoshinaka from the city. After fighting his cousins at the bridge over the Uji, where the war began, Yoshinaka made his final stand at Awazu, in Ōmi province.

Final stages of the conflict
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 convinced to agree to a truce. This was a farce, as neither the Minamoto nor the Emperor had any intentions of waiting until the eighth day to attack. Nevertheless, this tactic offered the Emperor a chance to regain the Regalia and to distract the Taira leadership.

The Minamoto army, led by Yoshitsune and Noriyori, made their first major assault at Ichi-no-Tani, one of the primary Taira fortresses on Honshū. The fortress was surrounded, and the Taira retreated to Shikoku. However, the Minamoto were not prepared to assault Shikoku; a six-month pause thus ensued during which the Minamoto took the proper steps. 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.

It was not until nearly a year after Ichi-no-Tani that the main Taira fortress at Yashima came under assault. Seeing bonfires on the mainland of Shikoku, the Taira expected a land-based attack and took to their ships. This was a deceptive play on the part of the Minamoto, however, who lay in wait with their own navy. The Yashima fortress fell, along with the improvised imperial palace built there by the Taira, many of whom however escaped along with the Imperial regalia and the Emperor Antoku.

The Genpei War came to an end one month later, following the battle of Dan-no-ura, one of the most famous and important battles in Japanese history. The Minamoto engaged the Taira fleet in the Straits of Shimonoseki, a tiny body of water separating the islands of Honshū and Kyūshū. After a series of archery duels, hand-to-hand fighting broke out. 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. The Minamoto advantage was considerably enhanced by the defection of Taguchi Shigeyoshi, a Taira general who revealed the location of Emperor Antoku and the regalia. The Minamoto redirected their attention on the Emperor's ship, and the battle quickly swung in their favor.

Many of the Taira samurai, along with Emperor Antoku and his grandmother Taira no Tokiko, widow of Taira no Kiyomori, threw themselves into the waves rather than live to see their clan's ultimate defeat at the hands of the Minamoto.

Consequences
The Taira clan was destroyed, and the Minamoto victory was followed by the establishment of the Kamakura shogunate. Though Minamoto no Yoritomo was not the first to ever hold the title of Shogun, he was the first to wield it in a role of nationwide scope. The end of the Genpei War and beginning of the Kamakura shogunate marked the rise of military class and the suppression of the power of the emperor, who was compelled to preside without effective political or military power, until the Meiji Restoration over 650 years later.

In addition, this war and its aftermath established red and white, the colors of the Taira and Minamoto standards, respectively, as Japan's national colors. Today, these colors can be seen on the flag of Japan, and also in banners and flags in sumo and other traditional activities.

Battles

 * 1180 First Battle of Uji - regarded as the first battle in the Genpei Wars, the monks of the Byodoin fight alongside Minamoto no Yorimasa.
 * 1180 Siege of Nara - the Taira set fire to temples and monasteries, to cut supplies to their rivals.
 * 1180 Battle of Ishibashiyama - Minamoto no Yoritomo's first battle against the Taira. Minamoto Yoritomo loses the battle.
 * 1180 Battle of Fujigawa - the Taira mistake a flock of waterfowl for a sneak attack by the Minamoto in the night, and retreat before any fighting occurs.
 * 1181 Battle of Sunomatagawa - the Taira thwart a sneak attack in the night but retreat.
 * 1181 Battle of Yahagigawa - the Minamoto, retreating from Sunomata, attempt to make a stand.
 * 1183 Siege of Hiuchi - the Taira attack a Minamoto fortress.
 * 1183 Battle of Kurikara - the tide of the war turns, in the Minamoto's favor.
 * 1183 Battle of Shinohara - Yoshinaka pursues the Taira force from Kurikara
 * 1183 Battle of Mizushima - the Taira intercept a Minamoto force, heading for Yashima.
 * 1183 Siege of Fukuryuji - the Minamoto attack a Taira fortress.
 * 1183 Battle of Muroyama - Minamoto no Yukiie tries and fails to recoup the loss of the battle of Mizushima.
 * 1184 Siege of Hojujidono - Yoshinaka sets fire to the Hojuji-dono and kidnaps Emperor Go-Shirakawa.
 * 1184 Second Battle of Uji - Yoshinaka is pursued out of the capital by Yoshitsune and Noriyori.
 * 1184 Battle of Awazu - Minamoto no Yoshinaka is defeated and killed by Minamoto no Yoshitsune and Minamoto no Noriyori.
 * 1184 Battle of Ichi-no-Tani - the Minamoto attack one of the Taira's primary fortresses.
 * 1184 Battle of Kojima - Taira fleeing Ichi-no-Tani are attacked by Minamoto no Noriyori.
 * 1185 Battle of Yashima - the Minamoto assault their enemies' fortress, just off of Shikoku.
 * 1185 Battle of Dan-no-ura - the decisive naval battle ending the war.