The Genpei War (1180-1185) was the culmination of decades conflict between the Minamoto and the Taira - the two most powerful military clans of the time.  .  Here are the sequence of important events leading to the Genpei War. 

1156 Hōgen Rebellion - Reigning Emperor Leads a Rebellion Against His Own Government.

In 1156, the reigning Emperor lead a revolt against his own government.  This is very strange concept indeed.  However, understanding that the emperor is more often than not beholden to powerful external forces is an important concept for understanding Japanese History.

Anyway, in 1156, there was a very short war called the Hōgen Rebellion.  In this war, the reigning Emperor Go-Shirakawa (E#77), who almost 30 years old at the time and who you would think had control of the government, actually had to revolt against his handlers (Fujiwara clan) and some of the former emperors.  With the critical assistance of the two emerging and powerful military clans of the period - the Taira and the Minimoto clans - Emperor Go-Shirakawa conceptually free himself from control by the Fujiwara clan. However, as we will see, this new found freedom was quite short and limited.   Some herald the ascension of Emperor Go-Shirakawa (E#77) and the installation of the Minimoto and Taira clan member to positions high in the government as the first samurai lead governments.  To some extent this is true but it is a bit of an overstatement:

• First, it really is a dream to think that the emperor (based solely in some dictate or mandate from heaven) was able to "control" people who were more heavily armed.  My guess is that Nintoku (E#16) was quite the warrior.  Point being being a warriors was an integral part of "controlling Japan" back in the day.  Thy may not have been called samurai by they were warriors none the less.    
• Second, there were many times period to the 6th century where the government was heavy influenced if not at times run by the those who controlled "the military" or at least control "a powerful military".    For example Soga and Shotoku Taishi in the late 6th century. 
• Third is more a technical point.  The Samurai of this era did not really begin to get  full control of this government till 11 years after the Hougen Rebellion, when Taira no Kiyomori was appointed to the top position in government.

The Taira Consolidate Power

The 1156 Hōgen Rebellion was followed by three years in minor infighting.

• The Taira become the most influential family in Kyoto - the capital.
• Emperor Go-Shirakawa (E#77) was forced to abdicate and the Taira installed the 13 year old Emperor Nijō (E#78).  Conceptually, at this time, former Emperor Go-Shirakawa (#77) had reasonable amounts of influence over his grandson Nijō and the Taira.

 1160 Heiji Rebellion

This infighting culminated in the 1160 Heiji Rebellion which was essentially a "mini genpei war" meaning a mini war between the Gen (the Minamoto) and the Hei (the Taira).   In January 1160 (late 1159 lunar calendar) the Minamoto staged a rebellion who major battle was the Siege of the Sanjō Palace (Goshirakawa's Palace).    During this conflict, the Minamoto were quickly able to capture Emperor Go-Shirakawa (E#77) and Emperor Nijō (E#78).   This rbellion was a brief armed conflict in the capital, lasting less than a than a month but resulted in the 

• in a resounding defeat of the Minamoto
• the death of the Minamoto no Yoshitomo - the clan leader.
• definitive control of the imperial court passing to Taira, lead by Kiyomori no Taira.

Taira no Kiyomori - clan leader

Taira no Kiyomori was a great man and had children were a bit more successful, he probably would have been remembered more that way.  However, that did not happen. (to be seen later). 

He was rich and powerful, and this did not happen by accident.  He had a significant commercial base of operation in what is modern day Kobe (good port on the island sea) and from there had significant commercial interest that trade with China.  He amassed significant wealth.  For those who don't know Kobe, Kyoto, Osaka, Nara and all relatively close together.  Kobe to Nara is ____ kilometer.  Kobe to Nara is ____.  Average 100 kilometer from end to end.

1167 - Major Power Shift

After 1160 Heiji Rebellion, from 1160 to 1167, the conflicts between the Taira and Minamoto continued in a subdue form. 

However, in 1167 there was a major power shift that occurred sort of seamlessly.

In that year Taira no Kiyomori was appointed Daijō Daijin, chief minister of the government.  Taira no Kiyomori was the de facto administrator of the imperial government. This was the first time such a position filled by a person coming from a warrior family. 

• the Taira then forced the addiction of Emperor Nijō (E#78) and installed the 3 year old Emperor Rokujō (#79), who was conceptually being "handled" by his grandfather, former Emperor Go-Shirakawa (#77).
• AN IMPORTANT NOTE regarding the imperial bloodline.  Up to now, the Taira had been busy marrying and breeding there way into the imperial bloodline.  Same plan used by the Soga in the 6th century to gain power.  While these plans were going well, "a Taira by blood" had still not yet ascended to the throne.  As we will see though this would soon happen. 
• In 1168, Taira no Kiyomori had the 79th emperor (who was the 4 years old) replaced by a 7 year old child - Emperor Takaku (E#80) who mother was Taira no Shigeko and father was former Emperor Go-Shirakawa (E#77).

In many ways  (my theory), one could date "military control" of Japan from 1167 or 1168 and call Taira no Kiyomori the first "shougun".  However, since Taira was not the ultimate winner of the subsequent war nor writer of the history, it is generally not construed this way.  However, even though he never had the title "shougun", Taira no Kiyomori was really Japan's first "military dictator", considering he possessed all the power and ultimately determined who was emperor.

1177 - Shishigatani Affair - Former Emperor Tries to Depose Taira no Kiyomori

In 1177, retired Emperor Go-Shirakawa (E#77) attempted a depose Taira no Kiyomori (Daijō Daijin / prime minister).   This is called the Shishigatani Affair.  The plot was not successful:

• Kimomori killed many of the plotters, including one monk.
• Kiyomori officially ended the Insei system - a legal system whereby abdicating emperors still had some sort of power.   
• Go-Shirakawa was allowed live (freely) but without the official power previously afforded him by the Insei System
• The Taira then began a series of executions, intended to eliminate their rivals.
• IMPORTANT NOTE:  Go-Shirakawa was still a free man at this time.  However, he was quite a trouble maker and would later find himself frequently "under house arrest" by more than one powerful military foe.  

December 1179 - Taira no Kiyomori  "arrests" the Former Emperor

Go-Shirakawa continued to cause trouble for the Kiyomori and by year end Kiyomori had had enough.  In December 1179, Kiyomori marched into the capital with several thousand troops and placed Go-Shirakawa "under house arrest".  He then a) forced the resignation of his rival from all government post and subsequently banished them, b) numerous high officials were reduced in rank and c)  replaced open positions with relatives or allies.

March 1180 - Taria Install a New Emperor.

3 months later, on March 21, 1180, Taira no Kiyomori forced the abdication of Emperor Takakura - who was the 80th emperor from age 7 and put his 2 year old grandson, Antoku (E#81) on the throne. 

May 1180 - "War is Declared".

Conceptually the Taira had disenfranchised a large percentage of the imperial court and was fiercely hated by them  Prince Mochihito was one of the "formerly in" "currently out" crowd.   Prince Mochihito, who was former emperor Go-Shirakawa's son and former emperor Takakura's brother, 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 on May 5, 1180 - conceptually the start of the Genpei War. 

June1180 - the 2 year old emperor & capital is move to Kobe.

In June 1180, on the eve of the first major battles of the Genpei war. Kiyomori moved the seat of imperial power to Fukuhara, which is modern day Hyougo-Ku in Kobe, just west of Sanomiya is a place historically know as the Owada-no-tomari (Ōwada Anchorage or Hyōgo Port). 

Fukuhara (Kobe) was Kiyomori a "Taira power base".  It is difficult to image these days as Kobe seems so off the beaten path compared to Nara and Kyoto, but Kobe was really a happening place, not to mention very strategically positioned - good port, restricted access from land, closest point to Shikoku - one off Japan's 4 large main islands - on along the inland seaway which was historically used for trade between "Osaka Area" and China / Korea. According to written record, the area has been an active history from 200 AD and the location of numerous old story or folklore.  One important note is that people traveling to and from the "Osaka Area" and "Kyuushu" and who follow the coast of foot are push into a narrow strip of beach between the mountains and the water by topography.  And its narrowest, it is perhaps only 1 mile wide.  Hence, conceptually, it a place that could be defended as a stronghold.  

This point was so obvious to those in power that the Tokugawa shogunate prohibited a castles from being build there and this "rule" may have been in effect for a much longer time - it just that I haven't found such references.  Also, in 1180, records indicate that the Kobe area had built a new port and was the center of trade with the Chinese Song Dynasty and the location of the Chinese embassy.   However, another reason for moving the imperial court to Kobe is to even more further remove former emperor Go Shirakawa, whom was still making the usual trouble for Taira no Kiyomori and thus still being held prisoner.  The Chinese influence can not be understated.  In a passage in the Hyakirenshō, is one of the first mentions of the growth of monetary transactions in Japan. ("There is a strange sickness going round the country nowadays. It is called the money disease.")  The use of coins increased quickly and by the end of the 13th century Chinese copper cash is legal tender for the payment of taxes and for use in private transactions.

War Begins

Battle of Uji

Anyway June 1180 was a busy month, but not a good one to be a rebel.  Prince Mochihito had fled Kyoto and had taken refuge up near Lake Biwako (Just North of Kyoto) and being protected by the Buddhist monks at in Mii-dera / Onjō-ji at the foot of Mt Hiei.  In June 1180, Taira forces went after Prince Mochihito who then with the help of the warrior monks of Mr. Hiei fled south in the direction of Nara.   Anyway, at the Battle of Uji, Prince Mochihito was killed along with the then Minamoto clan leader Minamoto no Yorimasa.    The Taira moved against the warrior monks of the Enryaku-ji complex on Mt Hiei but were not sucessful.  Hence they fough it easy to just attack the southern monks in Nara (see below) whose facilities were mostly in the valley.    Without getting into detail.  These Mt. Hiei monks show up frequently in Japanese History. Since there facilities are spread out all over this relative large and steep mountain area, they have historically been very difficult to defeat.  

Seige of Nara

Because the Buddhist assist Prince Mochihoto and the Minamoto, the Taira went on to Nara (the former capital) and attacked the "southern monks".    The summer of 1180, the Taira large force destroyed almost every major monastery and temple in Nara.  The warrior monks really did not have much chance.  Temples destroyed included the Toudai complex with it's Great Buddha Hall which at the time was purposively the largest wooden building in the world, houses the world's largest  Buddha statue.  The Koofuku-ji another important temple built in 669 AD before Nara was the capital was also destroy.  Approximate 3,000 monk died. 

Yorimoto becomes Clan leader & The battle of Ishibashiyama

After the death of Minamoto no Yorimasa, "Minamoto Yoritomo" become clan leader. However early on, in what would be one of the bloodiest battle of the war the battle of Ishibashiyama  (September 14, 1180) , Yoritomo is defeated and driven back to Kamakura.    History as told, says there was a truce and Yoritomo hung out in Kamakura and "reorganized"   There were a few samll battles in 1180 with the Taira chasing opposing forces toward Karakura - a Minamoto stronghold.   However, the Taira retreated back to Kyoto after the a small "non battle" called the Battle of Fujigawa in November 1180. 

Return to Kyoto

With the safety of Kyoto relatively secure from the Minamoto, the Taira move rht e capital back to Kyoto.

February 1181

In February 1181, Taira no Kiyomori became sick and died at the age of 63.  Legend has it that at the time of his death, suffering from fever, Kiyomori was confronted by a vision of hell and the ghosts of his victims.  Further still, Kiyomori's fever was so high that anyone who attempted to even get near him would be burned by the heat & his corpse had to be left to cool for several hours before it could be removed.  

Kiyomori's eldest son, the popular and talented Taira no Shigemori had did earlier in (1179).  Henc control of the clan passed to the much less capable Taira no Munemori (then 34 yars old) who who would presides over the downfall and destruction of the Taira at the hands of the Minamoto in 1185.  << RESEARCH DEATH>>

Summer 1181

Munemori inherited a war in a state of standstill - sort of a defacto cease fire caused by a) lack for food supplies cause by poor weather had devastated the crops of 1180 and 1181 and b) lack of initiative on all side. 

For the Taira in Kansai and for Minamoto no Yoritomo in Kamakura, separated by significant distance. there were no compelling reason to engage ach other. 

However, for Minamoto (Kiso) no Yoshinaka, a young and talented potential future clan laeader was really no reason to stop. He had led an army out of Shinano, marching into and controled Etchû, Kaga, and Echizen.

Minamoto no Yoritomo from his stronghold in Kamakura proposes to the Taira that the the country be split in two however this proposal was not seriously considered.

Summer 1183

The summer of 1183 was the beginning of the end for the Taira.  That summer, rice supplies had partially recovered from the previous failed growing seasons.   Taira no Munemori  decided to take an offesive against Minimoto no Yoshinaka position in Echizen.   Taira no Munemori dispatched his son Taira no Koremori and his brother Taira no Michimori to Echizen with the aim of pushing back Minimoto no Yoshinaka.  The campaign got off to a decidedly bad start-evidently,

• Logistical issues regarding food
• Poor training

Needless to say, the resulting Battle of Kurikara (June 1183) ended as a crushing Taira defeat.  It was the turning point in the war.  With a single battle, the Minimoto under the leadership of Minamoto no Yoshinaka had gained decisive advantage.  

History said that Taira no Munemori attempted to enlist the support of warrior-monks of Mt. Hiei.   Although the Minamoto had at times be enemies of the Minamoto, the Taira were now more of there enemy.  Hence, the the warrior monk emphatically refused. 

The Taira returned to Kyoto, packed up most of the royal family, and the Royal Regalia, and fell back to fortified positions in Settsu Province (Kobe). 

The Taira spend the fall of 1183 strengthening positions in Settsu Province (Kobe) and establishing fall back positions on Shikoku near present day Takamatsu. 

 

http://www.samurai-archives.com/munemori.html