The Battle of Dannoura (壇ノ浦の戦い)

The battle of Dannoura was fought in the closing days of the Heian period, on April 25, 1185, under the old lunar calendar), and took place in Nagato Province, at Akamaseki, Dannoura (modern-day Shimonoseki, Yamaguchi Pref.). It was the final battle of the rebellions of Jisho and Juei.

Background
In July, 1183, the Taira troops, that had been attacked by MINAMOTO no Yoshinaka, together with Emperor Antoku and the three Imperial Regalia and departed from Kyoto, but thereafter took advantage of their conflict with MINAMOTO no Yoritomo, who was in charge of the government at Kamakura, and Yoshinaka to stage a comeback of Taira support extending as far as Fukuhara of Settsu Province. However, they were dealt a crushing defeat in the battle of Ichinotani, which occurred in March, 1184, and fled by way of the sea, establishing strongholds at Yashima in Sanuki Province and Hikoshima in Nagato Province (today's Shimonoseki, Yamaguchi Pref.).

The political administration at Kamakura chose Yoritomo's younger brother MINAMOTO no Noriyori to lead 30,000 riders and advance along the Sanyodo Road, cross over into Kyushu, and adopt the strategy of blockading the Taira clan's army from the rear. But Noriyori's army, lacking sufficient provisions and opposed by the Taira's superior naval might, was forced to halt its advance, and could not even cross into Kyushu. Because of this, Yoritomo formed together a separate force for MINAMOTO no Yoshitsune and had them attack the Taira at their stronghold on Yashima in Sanuki Province. In March, 1185, Yoshitsune captured Yashima by means of a surprise attack (in what is known as the battle of Yashima). TAIRA no Munemori, the supreme commander of the Taira clan, took Emperor Antoku and fled via the sea to Hikoshima.

Noriyori's army, on the other hand, having succeeded in being supplied with provisions and warships, crossed over into Kyushu and defeated the Taira forces of that region in the battle of Ashiyaura, and successfully cut off the main Taira clan's army from behind. The Taira clan's army was left isolated at Hikoshima.

Progress of the Battle

In the "Azuma kagami" (Mirror of the East), the official (or semi-official) diary of the Kamakura Shogunate, the battle of Dannoura, listed under the entry of 24th day of the third month of Genryaku 2, is described as follows: 'The ships of the Minamoto and Taira, their forces apart from each other by approximately 300 meters, met in battle on the sea of Dannoura in Akamaseki of Nagato Province. The Taira clan split their 500 ships into three fleets, and with Hyotoji Hideto YAMAGA as well as Akira MATSUURA as the generals in command, challenged the Minamoto clan to fight.
At the hour of the Horse (around noon), the battle turned against the Taira clan, and it ended in their defeat.'
This is all the concisely written entry has to say, so nothing is known of the progress of the battle in any greater detail. Hence, there is no choice but to describe the progress of the battle relying on hearsay, and based on war chronicles like the "Heike monogatari" (Tale of the Taira) or "Gempei monogatari" (Chronicle of the Rising and Falling fates of the Minamoto and Taira clans), despite the fact that such chronicles are plagued with credibility issues.

Furthermore, the progress of the battle given below is based on the now widely accepted tidal theory first proposed in the Taisho period by Katsumi KUROITA, professor at Tokyo Imperial University.

The Battle Begins
Recognizing that he needed to destroy the Taira navy at Hikoshima, Yoshitsune managed to assemble a force of 840 ships (according to the "Azuma kagami") by calling together support from his allies, including the Watanabe navy of Settsu Province, the Kawano navy of Iyo Province, and the Kumano navy of Kii Province.

According to the "Heike monogatari," leaders at the war council held before the battle wished to have commander Kagetoki KAJIWARA lead the vanguard in the battle, but Yoshitsune spurned their advice and appointed himself leader of the vanguard. Kagetoki reportedly said, 'Never have I heard of the commanding general leading in the vanguard. That's not what generals are for,' mocking Yoshitsune until they were on the verge of coming to blows; this is the slander that Kagetoki conveyed to Yoritomo later, and was partially responsible for Yoshitsune's ruin.

The Taira clan had 500 ships (according to the "Azuma kagami"), which were divided into 100 under Akira MATSUURA, 300 under Hyotoji Hideto YAMAGA, and 100 under the command of Taira clan members (according to the "Heike monogatari"). Munemori's younger brother TAIRA no Tomomori took overall command as admiral. According to the "Heike monogatari," Tomomori hid soldiers on the large Chinese ship that was normally the Taira flagship, and where Emperor Antoku usually was, as part of a stratagem to lure the Kamakura warships in and surround them.

On May 2, the Taira navy under the command of Tomomori sallied forth from Hikoshima in response to Yoshitsune's attacking navy, and at the hour of the horse (about noon - according to the "Gyokuyo chronicle"; the "Azuma kagami" claims it was during the morning) the two navies clashed at Dannoura in the Kanmon straits, and the battle was joined.

Noriyori took about 30,000 horsemen (according to "the Chronicle of the Rise and Fall of the Minamoto and the Taira") from his army and drew up his battle lines on land to cut off the Taira's avenue of retreat, supporting Yoshitsune's army by shooting arrows long-distance from the cliffs. In the "Heike monogatari," Yoshimori WADA mounted his horse and rode out from the beach into the open sea, firing arrows long-range at a distance of more than 200 or even 300 meters.

The Taira Start to Prevail
The changing of the tides in the Kanmon straits is very strong, and the Taira navy, who had a thorough understanding of the tides there, was able to ride the rapid tidal current and rain down arrows on the enemy, and kept pushing back the Yoshitsune's army, the warriors from the east Japan, who were unused to fighting at sea. Yoshitsune's fleet was driven back as far as the area around the islands of Kanju and Manju, and taking advantage of their momentum, the Taira forces renewed their attack, trying to kill or capture Yoshitsune himself.

Recognizing his perilous disadvantage, Yoshitsune ordered his men to shoot the navigators and oarsmen of the enemy vessels. At this point in history, the shooting of noncombatants like navigators or oarsmen in a naval battle was considered against the etiquette of war, yet Yoshitsune dared to break this unwritten rule. Having lost their oarsmen and thus their means to direct their course, the Taira forces were thrown into confusion, and just then Yoshitsune's army made their attack; the brave among the east Japan soldiers boarded the enemy ships and engaged them in hand-to-hand fighting. According to the "Heike monogatari," it was at this moment that 300 navy ships of Shigenori AWA switched sides, turning against the Taira clan. Shigenori AWA had already revealed the ruse of the Taira's Chinese flagship to Yoshitsune, while led to the failure of Tomomori's strategy. But according to the "Azuma kagami," Shigenori AWA numbered among the prisoners of war in the battle, and nothing at all is mentioned of any treachery by him.

The Counterattack of the Minamoto clan and the Downfall of the Taira clan
Eventually, the tidal current turned, and when it did, Yoshitsune's navy rode the current and pushed back the Taira clan's army. This spelled catastrophe for the Taira army, and their defeat was assured. After they recognized the reality of their defeat, the members of the Taira clan started throwing themselves into the sea one after another.

The "Heike monogatari" describes the circumstances of how the Taira clan met their end.
Tomomori crossed over to the women's vessel, of which TAIRA no Tokuko and TAIRA no Tokiko were aboard, and laughingly said 'Get rid of anything unsightly and purify yourselves - and then I shall take you before this unusual man from the East.'
Upon hearing this, Tokiko (also known as Nii no ama, the Nun of the Second Rank) and others resolved to end their own lives, and holding the child Emperor Antoku tight, Tokiko girded the treasured sword (one of the three Imperial regalia) around her waist and seized the Grand Jewels. When Emperor Antoku looked up at her and asked, 'Where are we going?' Tokiko replied, 'Let us go to the Pure Land of Amidabha. His celestial city can also be found under the waves,' and so saying, jumped into the sea holding Emperor Antoku. According to the "Azuma kagami," Tokiko jumped holding the Sword and Jewels, while it was Lady Azechi who jumped holding Emperor Antoku. After that, other women of the Taira clan, including Tokiko's daughter Tokuko (also known as Kenreimonin, the Cloistered Lady of Kenrei Gate), threw themselves into the sea one after the other.

Many warriors also having readied themselves for the end; TAIRA no Norimori leapt into the sea, while TAIRA no Tsunemori briefly climbed up onto land and took the tonsure before he also jumped into the sea. Three other Taira warriors, Sukemori, Arimori, and Yukimori, also drowned themselves.

Munemori, the supreme commander of the Taira clan, and his eldest son and heir Kiyomune both tried to drown themselves, but they held their lives too dear and floated back to the surface; being skilled swimmers, they survived to be captured by Yoshitsune's forces.

The strong warrior TAIRA no Noritsune fought on like a demon, striking down the warriors from east Japan left and right, but Tomomori told him that, with the battle already lost, he should not do anything wicked. Noritsune replied that in that case, he wanted to take the enemy commander Yoshitsune down with him into the grave to keep him company, and after locating Yoshitsune's flagship, he leapt aboard. Noritsune, grasping both short and long swords, tried to get Yoshitsune to fight him in a duel, but Yoshitsune lightly sprang away, jumping away from ship to ship until he was eight ships distant.
This is Yoshitsune's famed 'Leaping of the Eight Ships.'
Munemitsu AKI, known for his great strength, tried to lay Noritsune low after Yoshitsune escaped and thus prove his merit, and joining with another man of equal strength, proceeded to grapple with Noritsune. After kicking one of them overboard into the sea, Noritsune himself leapt into the water still grappling with the second man. The above is the account given in the "Heike monogatari" of the final moments of Noritsune, known as the greatest of the strong leaders of the Taira clan and a thorn in Yoshitsune's side at both the battle of Okushima and at Dannoura, yet in the "Azuma kagami," Noritsune is recorded as having been killed during the battle of Ichinotani. In the "Daigo zatsuji ki" (The Record of the Finest Miscellaneous Matters of Life), however, Noritsune's name is listed among those who perished at Dannoura.

Tomomori muttered 'I have seen now what must be seen' and strapping on an extra suit of armor, he drowned himself together with his foster brother.

By the hour of the Monkey (around 4 PM - according to the "Gyokuyo." In the "Azuma kagami" the time is given as the hour of the Horse, or about noon), most of the Taira clan had died or been captured, and the battle ended in a victory for the Minamoto clan.

Aftermath of the Battle
Tokuko, who had jumped into the sea, was rescued and brought up again, and while the Eight-Span Mirror (Yata no kagami, one of the three Imperial Regalia); it was also known as the Naishidokoro (the Palace of the Inner Attendants, where it was kept) and the Grand Jewels (Yasakani no magatama, comma-shaped jewel) were recovered, Emperor Antoku, who had gone into the sea with Tokiko, perished, and the Sword (the Sword of the Heavenly Gathering of Clouds, the third of the Imperial Regalia) sank away into the sea (there is another theory which states that the Sword is still extant).

Emperor Antoku's half-brother (of a different mother), Imperial Prince Morisada (who had been appointed Antoku's crown prince), was rescued. Of the Taira clan those taken prisoner included Munemori and Kiyomune; the courtiers TAIRA no Tokitada (Tokiko's younger brother), TAIRA no Tokizane, TAIRA no Nobumoto, and FUJIWARA no Tadaaki, who had acted in support of the main Taira clan; the Buddhist priests Noen, Zenshin, Ryoko, Chukai, and Gyomei; the military commanders TAIRA no Morikuni, TAIRA no Morizumi, and MINAMOTO no Suesada; and among the women, FUJIWARA no Sukeko (known as the Lady-in-Waiting to the Chief Councillor of State (Dainagon)), FUJIWARA no Muneko (the Lady-in-Waiting to the governor), and the Lady-in-Waiting to the Lord of the Office of Governance.

Yoshitsune returned to the capital accompanied by Tokuko and Imperial Prince Morisada as prisoners of war, while Noriyori remained in Kyushu, meting out postwar punishments. After Yoshitsune made his triumphal entry into the capital, the Retired Emperor Goshirakawa bestowed honors and court appointments upon him and his gokenin vassals. When he learned of this, Yoritomo fell into a rage, and forbade those who had received appointments from returning to their homes in the eastern provinces. What's more, a letter then arrived from Kagetoki KAJIWARA, who had remained in Kyushu, to Yoritomo bringing formal complaint against Yoshitsune for his haughtiness and tyranny during the war to hunt down and destroy the Taira clan, and having been informed that Yoshitsune had also taken the daughter of TAIRA no Tokitada to be his wife, Yoritomo was angered still more.

In June, 1185, Yoshitsune disobeyed Yoritomo's order and headed for Kamakura City under the pretense of escorting Munemori and his son Kiyomune there, but was stopped at Koshigoe. Munemori and his son were sent along to Kamakura alone to meet with Yoritomo. Yoshitsune wrote his famous Koshigoe Letter and asked Yoritomo's forgiveness, but the following month he was sent off back to the capital with Munemori and his son in tow. Munemori and his son Kiyomune were beheaded in Omi Province while they were en route back to the capital.

Thereafter, Yoshitsune did not obtain Yoritomo's forgiveness, and their faceoff grew worse, until in November, Yoshitsune went to attend the Retired Emperor Goshirakawa, who issued an Imperial decree that Yoritomo be hunted down and killed, whereupon Yoshitsune raised an army, but was defeated. After this another Imperial decree was issued, yet this one was issued against him, commanding that Yoshitsune himself be hunted down; facing ruin, he fled to his Fujiwara ally in northern Japan, but in April, 1189, he was assassinated in the town of Hiraizumi.

Immediately after the battle, Tokuko became a nun and began a secluded life in Ohara. Imperial Prince Morisada, having already been cut out of the Imperial succession, afterwards took the tonsure. TAIRA no Tokitada was banished to Noto Province, where he died.

This battle marked the end of the 25-year political hegemony of the Taira clan (specifically, the relatives of Kiyomori in the Ise branch of the Taira clan). The victorious leader of Seiwa-Genji (Minamoto clan), Yoritomo clans, created the warrior-based Kamakura shogunate in the city of Kamakura.

Composition of the two opposing armies
The Minamoto side
Commanding generals: on land, MINAMOTO no Noriyori; at sea, MINAMOTO no Yoshitsune. Size of fleet: 800 ships according to the Azuma kagami, or 3000 ships according to the Heike monogatari. Other military commanders who took part in the battle: Kagetoki KAJIWARA, the monk Tanzo, Michinobu KONO, and Yukitsuna TADA.

The Taira side
Commanding general: TAIRA no Munemori
Size of fleet: 500 ships according to the Azuma kagami, or 1000 according to the Heike monogatari. Other military commanders who took part in the battle (all of whom were of the Taira clan): TAIRA no Tomomori, Tsunemori, Norimori, Noritsune, Sukemori, Arimori, Yukimori, Tokitada, Kiyomune, and Kagekiyo.

The Theory that the Tides Changed
This theory holds that the changing of the tides in the Kanmon straits held the key to victory or defeat. However, it goes without saying that the "Azuma kagami," which only describes the battle in a very simple, brief manner, doesn't mention the tides at all. The "Heike monogatari," a war chronicle, records that 'Since the tides at Monjigaseki and Dannoura flowed powerfully out, the Taira ships rode the tide and sallied forth. The Minamoto ships had to push against the current,' thereby claiming that the tide was with the Taira and against the Minamoto as they fought, but still doesn't go so far as to say that the reversing of the tidal current's direction led to a reversal in the fortunes of the two sides.

The present well-known theory that the effect of the changing tides decided the battle was first advanced by Katsumi KUROITA, professor at Tokyo Imperial University, in his work entitled "The Legends of Yoshitsune" in 1914.

Regarding the time the battle is thought to have taken place, the "Azuma kagami" has it as ending by the hour of the Horse (around noon), while the "Gyokuyo," the diary of the Kampaku (Chief Advisor) Kanemitsu KUJO, records it as beginning at noon and ending by the hour of the Monkey (around 4 PM).

Katsumi KUROITA, based on an investigation conducted by Tokyo Imperial University's naval hydrographic department into the tidal currents on May 2, 1185, proved that the westward tidal current in the Kanmon straits started flowing eastward at 8:30 in the morning, reaching a speed of eight knots by around 11 AM, and returned to flowing westward at around 3 in the afternoon; asserting that the times given in the "Gyokuyo" for when the battle was fought (from noon to 4 PM) were correct and thus that the battle took place in the afternoon, he further stated that as long as the current was flowing east the Taira clan had the advantage, but after it switched back to flowing west, there was a reversal of fortunes and the Minamoto clan gained the upper hand.

Katsumi KUROITA's theory of the battle of Dannoura marked the first time such a theory had been verified by scientific data, and consequently was seen as very authoritative, leading to its widespread acceptance. Depictions - including novels, sightseeing pamphlets and so forth, and of course TV dramas - that deal with this battle, and even history-related academic publications on the Gempei War (the war between the Minamoto and the Taira clans) all show the battle from the standpoint of KUROITA's changing tides theory.

Concerning KUROITA's theory, in recent years objections to it have surfaced; in 1990 the maritime historian Dr. Shozo KANASASHI ran a computer analysis of the tides on the day of the battle, and concluded that there was a neap tide that day, and thus that there could not have been a strong, swift current of eight knots, and moreover pointed out that the tidal study done in the Taisho period had been conducted at the narrowest point of the Kanmon straits (where it would have been impossible for more than 1000 ships to fight), concluding that in the spacious area of sea near Kanju and Manju islands, the tide was under one knot in speed and would have had no influence over the course of the battle.

A study conducted by the Japan Coast Guard also found that the current in the area east of the Kanmon straits, where the battle was fought, was under one knot.

The naval historian Kenji ISHII also pointed out that if ships were riding the same current, their relative velocity would not change, and thus that the current had no effect on the course of the battle. And Yukihito IIJIMA, professor emeritus at Tokyo University of Marine Science and Technology, criticized the changing tides theory by also asserting the view that tidal speed has no effect on the relative velocity of ships riding the same current.

And right from the outset, the view that, there being no reason to question what the "Azuma kagami" - the official record of the Kamakura Shogunate - claimed, the battle thus must have been fought in the morning and had ended by 12, is strong and deeply rooted.

The theory that the Sword of the Heavenly Gathering of Clouds was lost at the bottom of the sea
The entry in the "Azuma kagami" for the 24th day of the third month of Genryaku 2, which concerns the battle of Dannoura, states that 'Tokiko held the treasured Sword, and Lady Azechi reverently held Emperor Antoku close, and then they jumped together and sank away to the bottom of the sea.'
This episode is also described in a very similar way in the Heike monogatari. Furthermore, after the battle, the entry for the eleventh day of the fourth month of Genryaku 2, which reports on those of the Taira faction that died in battle or were captured, also records that 'The Eight-Span Mirror and the Grand Jewels have arrived. But the treasured Sword has been lost.
I will respectfully search among the prisoners of war.'
In general, this seems to suggest that of the Imperial Regalia, the Sword was lost at one point at the battle of Dannoura. This version of events is what is depicted in novels, TV dramas and so forth; in the 35th episode of NHK's Taiga drama "Yoshitsune" (2005), 'The deciding battle at DannoUra,' Keiko MATSUZAKA, playing the role of Tokiko, sinks into the sea holding Emperor Antoku and the Sword, clearly showing the Sword being lost at the bottom of the sea.

Research in Recent Years
In 2005, as part of the Kadokawa anthology, Kazunori HISHINUMA (a researcher at Japan's National Museum of Japanese History) published a book entitled "MINAMOTO no Yoshitsune's Battles and Strategies: the Legends and the Real Account;" in it, he advances the following theory.

Yoshitsune, fresh off his victory at the battle of Okushima in March, 1185, spent a month resupplying and readying his army, and won over warriors possessing significant naval forces like Tsunenobu KANO and Masatoshi FUNATO as allies, establishing his control over the Seto Inland Sea. Meanwhile, the Taira family, for whom Hikoshima was their only remaining stronghold, were unable to adequately resupply their troops with provisions and weapons. Moreover, their avenue of retreat into Kyushu had been cut off by the army of MINAMOTO no Noriyori, who had crossed into Bungo Province.

The battle began around noon. Both armies would probably have wanted to choose a time where they could navigate their ships as free of the influence of the tidal current as possible. The Taira forces made the opening attack, in which they fired so many arrows they stopped the Kamakura forces in their tracks, and were more than holding their own in the battle, but once they ran out of arrows, they were attacked in turn by Yoshitsune's archers on sea, and Noriyori's archers on land, and the Taira were mowed down, starting with their boatmen and rowers, who lacked adequate defensive equipment. As a result of losing their oarsmen, the Taira ships could no longer control their movement, and seeing the Taira clan at such a disadvantage, many warlords flocked to switch sides and join the Kamakura forces.

Having accepted the reality of their defeat, the Taira family began jumping into the sea, one after another. A Taira defeat was inevitable after Noriyori's army took control of Kyushu and Yoshitsune's army of Shikoku, which let the Kamakura side retake control over the Seto Inland Sea and thus complete their encirclement and isolation of the last Taira stronghold.