Most of Japan’s provinces are overseen by just a governor, but Mutsu province, in what is now the Tohoku region, has a military general in charge of controlling the Emishi natives, thought to be related to the Ainu, who had been subjugated in the ninth century when the Japanese took over the area.

Historically, this post has always been held by a member of the Abe clan, and there have been many conflicts between the Abe general and the Governor over administrative control of the province.

Abe no Yoritoki, the general overseeing the Ainu in 1050, had levied taxes and confiscated property on his own, rarely paying any heed to the wishes of the province's governor.

The governors of Mutsu and Dewaz provinces join forces against the Abe and march against them in 1051, but the Abe defeat their army and force their withdrawal.

The Governor had sent word to the capital in Kyoto asking for help, and as a result Minamoto no Yoriyoshi is appointed both Governor and commander-in-chief over controlling the natives.

He is sent with his son Yoshiie, then age fifteen, to stop Abe.

The fighting will last for twelve years, or nine if one subtracts short periods of ceasefire and peace.

An arrow kills clan leader Yoritoke Abe in the first engagement in 1056.

His son Sadato assumes command and continues the war.

Skirmishes have been fierce and many, but few major battles have been fought until the battle of Kawasaki in 1057.

Abe no Yoritoki had been killed shortly before, and the Minamoto are now fighting his son, Abe no Sadato, who annihilates them at Kawasaki and pursues them through a blizzard; only a handful of survivors, aided by a snowstorm, escape.

Minamoto no Yoriyoshi and his son Yoshiie had come to the Abe clan's northern province of Mutsu to restore power over the province to the Governor; Abe no Yoritoki, Sadato's father, had been acting beyond his station.

As a result, the two clans have fought for roughly nine years, with some truces, over the course of the past eleven years, in the conflict known as the Zenkunen War, (later known in English as the Former Nine Years’ War).

Yoritoki had been killed in 1057, and so Sadato had become head of the Abe clan and head of the military effort against the Minamoto.

He had fought them in the battle of Kawasaki, in a snowstorm, defeated them and pursued them through the blizzard for a short time.

Other battles have followed, during which Sadato's attacks, along with the harsh weather and terrain, have weakened his enemies.

The Minamoto clan, supported by the Japanese government, has recovered from the disaster at Kawasaki to resume the war, returning to face Abe Sadato with a fresh army and ten thousand additional men from the Kiyohara clan in nearby Dewa province.

The second Abe son soon surrenders to the Minamotos and is exiled, but Sadato fights on.

Abe Sadato, defeated in two battles, makes a stand at his base in Kuriyagawa in 1062.

Minamoto no Yoriyoshi, along with his son, leads an assault.

They divert the water supply, storm the earthworks and stockade, and set the fortress aflame.

After two days of fighting, Sadato surrenders.

The Minamoto will return to Kyoto the following year, carrying Sadato’s head to the emperor.