An Army That Fled Before the Battle
The Battle of Fujigawa (1180) and the Truth Behind the ‘Waterfowl Story’

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In 1180, Minamoto and Taira forces clashed for the first time at the Battle of Fujigawa. Behind the famous anecdote of “Taira warriors panicking at the sound of waterfowl” lies a very real political and military crisis. This piece revisits that moment—when Minamoto no Yoritomo’s Kamakura regime was just beginning to take shape—through primary sources like Azuma Kagami, Heike Monogatari, Gyokuyō, and modern scholarship.

The Battle of Fujigawa (1180)

How True Is the Legend of “Warriors Who Panicked at the Sound of Waterfowl”?

When people in Japan talk about the Genpei War (Jishō–Juei no Ran), one scene almost always makes an appearance:

In the dead of night, a great flock of waterfowl takes off from the river.
The Taira army mistakes the sound for an enemy night attack…
And the whole force breaks and runs.

This is the famous anecdote attached to the Battle of Fujigawa (富士川の戦い).

But did hardened warriors of the late Heian period really lose their nerve over the beating wings of a few birds?

In this article, we’ll put the legend back into its context—looking at the political and military background, the key sources (Azuma Kagami, Heike Monogatari, Gyokuyō), and what recent research actually says about the battle’s meaning in Japanese history.

1. Background – The Taira Zenith and the Minamoto Comeback

(1) Kiyomori at the Top, and Resentment Everywhere

In the mid-12th century, Taira no Kiyomori rose to become the de facto ruler of the realm:

He crushed his rivals in the Hōgen Rebellion and the Heiji Rebellion.
He married into the imperial family and positioned his grandson as Emperor Antoku.
On paper, it became “Taira blood on the throne, Taira hands on the levers of power.”

But the price of that domination was growing resentment in the countryside.

Newly appointed Taira-backed governors and stewards pressed hard on the old provincial families. Across the eastern provinces, the mood was basically:

“The capital is fat and happy, the provinces are squeezed dry.
Someone is going to rebel sooner or later.”

Kiyomori had won the capital—but he was quietly losing the provinces.

(2) Prince Mochihito’s Call and the Rise of the Eastern Warriors

In 1180, Prince Mochihito (Mochihito-ō, 以仁王) issued a ryōji (imperial order) calling for the overthrow of the Taira.

That single call acted like a spark in dry grass:

In exile in Izu, Minamoto no Yoritomo raised his banner.
In Kai Province, Takeda Nobuyoshi and the Kai-Minamoto joined the cause.
In Shinano, Minamoto no Yoshinaka moved independently.

For our story, the key figure is Yoritomo—the man who will eventually found the Kamakura shogunate.

2. Yoritomo’s Early Defeat and His Choice of Kamakura

(1) The Defeat at Ishibashiyama and Flight to Awa

Yoritomo’s first move did not go well.

He rose in Izu… and was promptly crushed at the Battle of Ishibashiyama (1180) by Taira-aligned forces.
He barely escaped with his life, fleeing through the mountains.
Eventually he slipped across the sea to Awa Province, on the Bōsō Peninsula.

It was there that he began to rebuild, securing the support of powerful eastern families:

The Chiba clan,
The Kazusa clan,
And other regional warriors who hated Taira-era officials more than they feared failure.

From this point on, “the Minamoto in the East” starts to mean something more than a romantic slogan.

(2) Kamakura as a Natural Fortress

Yoritomo then made his key strategic choice: he moved his base to Kamakura.

Kamakura is:

Ringed by hills on three sides and open to the sea on the fourth,
A natural stronghold that’s easy to defend and hard to assault,
A region with spiritual and ancestral ties to Yoritomo’s line (Hachiman shrines, old Minamoto connections).

On 6 October 1180, Yoritomo entered Kamakura with almost no resistance. From that day on, Kamakura stopped being just another provincial town and started becoming a political concept: the future seat of a military government.

3. Three Forces on the Board – Yoritomo, the Kai-Minamoto, and the Taira Expedition

Just before Fujigawa, the map of central Japan essentially shows a three-cornered contest:

To the east – Yoritomo’s forces based in and around Kamakura.
To the north-east – The Kai-Minamoto under Takeda Nobuyoshi, controlling Kai, Suruga, and neighboring regions.
To the west – A Taira punitive expedition under Taira no Koremori, sent down from the capital.

(1) The Kai-Minamoto as Independent Actors

The later chronicle Azuma Kagami tends to write as if Takeda Nobuyoshi and the Kai-Minamoto were straightforwardly under Yoritomo’s command.

Modern historians are more cautious.

The emerging consensus is that:

The Kai-Minamoto rose in response to Prince Mochihito’s call as an independent anti-Taira force, not as Yoritomo’s vassals from the start.

In other words, at this stage they were more like allied rebels than subordinates. Yoritomo was a rising star in the east—but he was not yet the unquestioned commander of all Minamoto-aligned forces.

(2) Weaknesses of the Taira Army – Logistics and Morale

The Taira expeditionary force under Koremori, marching out from the capital, looked impressive on paper but had serious problems:

It was a hastily assembled mix of conscripted warriors and local levies.
Famine and shortages in western Japan made food supply precarious.
On the long march east, desertions began to mount.

Heike Monogatari talks about a force of 70,000 riders—but contemporary diaries like Gyokuyō paint a more modest picture: perhaps 2,000–4,000 warriors in the field, with the number shrinking as the campaign dragged on.

In short, it was already a beaten army walking—it just hadn’t broken yet.

4. The Battle That Wasn’t – Fujigawa as a Non-Battle

(1) Deployment on the Fuji River

In the 10th month of Jishō 4 (1180):

Takeda Nobuyoshi and the Kai-Minamoto advanced to the eastern bank of the Fuji River.
Koremori’s Taira army camped on the western bank.

According to Azuma Kagami:

Yoritomo himself set up camp farther back, around the Kisegawa area, watching developments and consolidating his hold over eastern warriors.

So if you zoom in on the front line, the immediate clash at Fujigawa was less:

“Yoritomo versus Kiyomori”

and more:

“Kai-Minamoto versus Koremori’s Taira punitive force,”
with Yoritomo positioned behind them as the political beneficiary of whatever happened next.

(2) The Famous Waterfowl Story – What Actually Happened?

The classic war tales (Heike Monogatari, Gikeiki, etc.) give us the cinematic version:

Under cover of darkness, the Kai-Minamoto lead their horses into the shallows of the river.
Startled, huge flocks of waterfowl explode into the air.
In the tense silence of night, the roaring of wings sound like an onrushing cavalry charge.
The already nervous Taira troops panic, throw away their equipment, mount whatever horses they can find, and bolt in every direction.

It’s a brilliant scene—and that’s exactly why we should be suspicious.

If we line up the more sober sources, a different picture emerges:

Gyokuyō says that hundreds of men deserted before any serious clash, and that Koremori, recognizing his numerical disadvantage, ordered a retreat.
Other court diaries report that the Taira troops, fearing encirclement, set fire to their own camp and withdrew under cover of darkness.
Azuma Kagami mentions fear of being cut off by the eastern forces and implies that the waterfowl episode triggered an already brewing collapse.
Heike Monogatari then polishes all this into the memorable legend of “warriors routed by bird wings.”

Taken together, the most plausible reading is:

The Taira army was already suffering from desertion, supply problems, and collapsing morale.
The noise of the waterfowl didn’t create panic from nowhere—it simply became the signal for a retreat that many in the army wanted anyway.

So the Battle of Fujigawa was, in reality, a “battle” in which:

The armies faced each other across the river,
One side’s will to fight evaporated,
And the Taira command decided—chaotically and poorly—to pull back without a pitched engagement.

It is, almost literally, a battle that ended before it truly began.

5. Aftermath – Yoritomo’s Grip on the East and the Foundations of Kamakura

Once Koremori’s force disintegrated and fell back westward, the strategic picture shifted quickly:

The Taira punitive army was effectively finished as an instrument of eastern control.
The Kai-Minamoto solidified their hold over Kai, Suruga, and the surrounding areas.
Yoritomo, from Kamakura, moved to eliminate rival eastern powers (such as the Satake) and assert himself as the leader of warriors in the Kantō and beyond.

Step by careful step, he:

Created new offices (like the shugo and jitō),
Institutionalized bonds of vassalage with eastern samurai,
And laid the groundwork for what would become the Kamakura shogunate.

From that angle, Fujigawa’s real importance is not the scale of the fighting, but this:

It was the moment when the Taira’s reputation for invincibility cracked in the East,
and when regional warriors began to see Yoritomo—and the Kamakura camp—as the safer bet.

6. “A Stupid War” or the Birth of Psychological and Structural Warfare?

It’s tempting to treat the whole thing as a punchline:

“An army that ran from the sound of birds—what an epic fail.”

On one level, that humor hits a real nerve: fear, rumor, and night terrors have always shaped battlefields.

But if we zoom out, a few deeper themes emerge:

The Taira army at Fujigawa was structurally doomed.
It was under-supplied, hastily assembled, and fighting far from its logistical base—while its opponents fought on home ground with rising local support.
The waterfowl story is probably a literary device, polished by war-tale authors to illustrate the Taira’s loss of nerve and the “rightness” of Minamoto ascendancy.
The battle’s real significance lies in the shift of power in the East—the consolidation of warrior rule and the beginning of a political order in which Kamakura, not Kyoto, would be the nerve center of military power.

So rather than seeing Fujigawa as just:

“a silly episode where a big army freaked out and ran,”

we can read it as:

a case study in how logistics, morale, and perception decide wars—
and as the opening chord in the long, uneasy music of samurai government that would dominate Japan for centuries.

A light history story

Sunday, November 23, 2025

An Army That Fled Before the Battle The Battle of Fujigawa (1180) and the Truth Behind the ‘Waterfowl Story’