Battle of Kojima

What Happened

On 10 January 1185, forces of the Minamoto clan crossed to the small island of Kojima, in the Inland Sea off the coast of what is now Okayama Prefecture, and destroyed a Taira garrison holding it. The Taira commander on the island was Taira no Yukimori. The Minamoto assault was led by Sasaki Moritsuna, a warrior of the Sasaki family of Ōmi Province.

The island was separated from the mainland by a shallow channel, and the Taira defenders expected the water to protect them. Sasaki Moritsuna found a local fisherman who knew where the channel could be forded, and crossed his horsemen over at low water. The Taira position was taken, and Yukimori's force was broken.

The action was small in scale but complete in result: the Taira lost the island and the men defending it.

Background

The Genpei War (源平合戦, Genpei kassen) was a civil war fought between two warrior houses, the Minamoto (源, also read Genji) and the Taira (平, also read Heike). It ran from 1180 to 1185 and ended with the destruction of Taira power and the establishment of the first shogunate under Minamoto no Yoritomo.

By late 1184 the Taira had been pushed out of the capital and driven west along the Inland Sea. They still held a chain of island and coastal positions on the sea route towards their strongholds in the west, and the Minamoto advance under Yoritomo's brother Minamoto no Noriyori had to reduce these one by one. Kojima was one of those positions.

The campaign fell in the first year of the Bunji era (文治, Bunji), a nengō (年号, year-name) that ran from 1185. The fighting of this final phase belongs to the closing months of the war.

Why It Mattered

Kojima mattered less for the numbers involved than for what it opened. Taking the island cleared a Minamoto path along the Inland Sea and stripped the Taira of a forward position covering the approaches to their remaining bases. The campaign that followed in the same year ended the war at the naval Battle of Dan-no-ura.

The battle is remembered in Japanese tradition chiefly for Sasaki Moritsuna's crossing. The story of a warrior obtaining local knowledge of a ford and using it to take an apparently impassable position became one of the best-known episodes of the Genpei War, retold in the war chronicles and in later puppet and kabuki drama. It is a compact illustration of how the Genpei War was often decided: not by massed slaughter but by one commander finding a way through terrain that the other side had counted on.

The victory also belongs to the political story of 1185. In that year Minamoto no Yoritomo consolidated military authority, and the institutions that became the Kamakura shogunate took shape. Kojima is one of the small engagements that made the Minamoto victory in the field complete.

The Name in Japanese

The Japanese name of the battle is 藤戸の戦い, read ふじとのたたかい (Fujito no tatakai). The same engagement is also called 児島合戦 (Kojima kassen), from the island's name.

Breaking the name down:

• 藤 — read fuji here. It means "wisteria", the climbing plant. The character also appears in the surname Fujiwara (藤原).
• 戸 — read to here. It means "door" or "gate", and by extension a household or an entrance. In place names it often marks a crossing point or a settlement at a passage.
• の — read no. This is the possessive particle, written in kana rather than kanji. It links 藤戸 to 戦い, giving "the battle of Fujito".
• 戦 — read tatakai here, in its kun reading. It means "war", "battle" or "fight". The same character is read sen in Sino-Japanese compounds, as in 戦争 (sensō, war).
• い — read i. The final kana completes the kun reading of 戦 as tatakai. The verb behind it is 戦う (tatakau, to fight).

So the whole name means, plainly, "the battle of Fujito". Fujito is the place: the ford and the crossing to the island. The alternative name 児島合戦 uses 児島 (Kojima), the island, plus 合戦 (kassen), "battle" or "engagement" — a compound of 合, "to join", and 戦, "battle".

For a learner, the useful points are that 戦い is the ordinary noun for a battle or fight, that の is the linking particle seen in countless Japanese titles, and that 合戦 is the more formal, chronicle-style word for a pitched engagement.

Key Figures

Sasaki Moritsuna (佐々木盛綱, Sasaki Moritsuna) commanded the Minamoto assault on Kojima. He is the central figure of the battle in Japanese memory, credited with finding the ford across the channel and leading his cavalry over it.

Taira no Yukimori (平行盛, Taira no Yukimori) commanded the Taira garrison on the island. His force was defeated in the engagement.

Minamoto no Noriyori (源範頼, Minamoto no Noriyori) was the Minamoto commander in the western campaign of 1184–1185, of which the Kojima action formed a part. He was a brother of Minamoto no Yoritomo.

Minamoto no Yoritomo (源頼朝, Minamoto no Yoritomo) led the Minamoto house and, after the war's end in 1185, established the shogunate at Kamakura that gave the following period its name.