Battle of Anegawa (1570): Nobunaga and Ieyasu vs. the Azai-Asakura Alliance. The dramatic clash along the Anegawa River and the answer to Azai Nagamasa’s betrayal.

In the summer of 1570, along the banks of the Anegawa River in Ōmi Province, the forces of Oda Nobunaga and his key ally Tokugawa Ieyasu clashed with the combined forces of the Azai and Asakura clans. The Battle of Anegawa was the first major tactical test of the Oda-Tokugawa alliance and a pivotal confrontation in Nobunaga’s struggle to dominate central Japan. Explore the background of this dramatic brother-in-law confrontation, the course of the battle, its historical significance, and a list of key samurai involved.

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The Battle of Anegawa (1570): Nobunaga and Ieyasu vs. the Azai-Asakura Alliance

In the summer of 1570, Oda Nobunaga and his crucial ally Tokugawa Ieyasu clashed with the combined forces of the Azai and Asakura clans along the banks of the Anegawa River in Ōmi Province. The Battle of Anegawa — known in Japanese as Anegawa no tatakai — was the first major test of the Oda-Tokugawa alliance and a pivotal confrontation in Nobunaga’s long struggle to dominate central Japan.

What made this battle particularly dramatic was its personal dimension: Nobunaga was fighting against Azai Nagamasa, his own brother-in-law, whose marriage to Nobunaga’s younger sister Oichi had been intended to seal a political alliance. The Azai’s sudden betrayal just months earlier — when they turned on Nobunaga during his campaign against the Asakura clan — had transformed a trusted ally into a dangerous enemy. Anegawa was Nobunaga’s answer.

In this article, we explain the background to the battle, the course of the fighting, and its lasting historical significance, closing with a list of the key samurai involved.

What Was the Battle of Anegawa?

The Battle of Anegawa took place on the 28th day of the 6th month of Genki 1 (approximately July 30, 1570), along the Anegawa River in Ōmi Province — in the area of modern-day Nagahama City, Shiga Prefecture.

The battle pitted the combined forces of Oda Nobunaga and Tokugawa Ieyasu against an alliance of the Azai clan of northern Ōmi and the Asakura clan of Echizen. The Oda-Tokugawa side won a clear victory, but the Azai and Asakura were not destroyed — both clans continued to resist Nobunaga until their final defeat in 1573.

Battlefield and Balance of Power

ItemOda-Tokugawa ForcesAzai-Asakura Forces
CommandersOda Nobunaga & Tokugawa IeyasuAzai Nagamasa & Asakura Kagetake
Estimated Troops~28,000 (various estimates)~18,000 (various estimates)
Oda alignmentOda vs. Asakura (right flank)Asakura facing Oda
Tokugawa alignmentTokugawa vs. Azai (left flank)Azai facing Tokugawa
Year1570 (Genki 1), approx. July 30
LocationAnegawa River, Ōmi Province (modern Nagahama City, Shiga Prefecture)
ResultOda-Tokugawa victory; Azai and Asakura weakened but survive until 1573

Background to the Battle

The Azai Betrayal and the Kanegasaki Retreat (Spring 1570)

To understand Anegawa, one must begin with the dramatic events of spring 1570. Nobunaga had launched a campaign against the Asakura clan of Echizen Province, who had refused to support his march on Kyoto. However, in a stunning reversal, his ally Azai Nagamasa broke their alliance and attacked the Oda army from the rear. Nobunaga was forced into a hasty retreat from Kanegasaki, a moment of acute personal danger that he barely survived.

  • Nobunaga had married his younger sister Oichi to Nagamasa in 1564 to cement the Oda-Azai alliance
  • The Azai clan had a prior agreement with the Asakura that they would not support any attack on Echizen — an obligation Nagamasa honored, even at the cost of his relationship with Nobunaga
  • The retreat from Kanegasaki was covered by a rearguard that included Kinoshita Tōkichirō (later Hideyoshi) and Akechi Mitsuhide, who helped prevent a complete disaster

The Formation of the Anti-Nobunaga Network

After the Kanegasaki retreat, Nobunaga faced a serious strategic situation. The Azai and Asakura combined to threaten him from the north, while other powerful enemies — including the Ikko-ikki religious leagues and the Miyoshi clan — pressed from other directions. The Battle of Anegawa was Nobunaga’s move to eliminate the immediate northern threat before it could coordinate with his other enemies.

The Oda-Tokugawa Alliance

Tokugawa Ieyasu, who had allied with Nobunaga in 1562 (the Kiyosu Alliance), brought a significant force to reinforce the Oda army. The battlefield assignment — Tokugawa facing the Azai, Oda facing the Asakura — reflected both the geographical position of the two enemy forces and the respective strengths of each allied contingent.

Course of the Battle

Scene 1 — Armies Converge at the Anegawa (July 1570)

The Azai-Asakura combined force advanced into Ōmi Province and took position on the far bank of the Anegawa River. Nobunaga and Ieyasu deployed their forces on the opposite bank, with the Oda contingent on the right and the Tokugawa on the left. Both sides prepared to force a crossing of the shallow but tactically significant river.

Scene 2 — Tokugawa Struggles Against the Azai

When battle was joined, the Tokugawa forces found themselves hard-pressed by the formidable Azai army under Nagamasa. The Azai clan’s warriors were among the finest in the region, and the Tokugawa contingent — though fierce — was in danger of being overwhelmed. Figures such as Honda Tadakatsu distinguished themselves in this desperate fighting on the Tokugawa flank.

Scene 3 — Oda Breaks Through the Asakura

On the Oda flank, Nobunaga’s forces attacked the Asakura contingent — commanded at the battle by Asakura Kagetake — and broke through their lines. The Asakura, outnumbered and outmaneuvered, collapsed faster than the Azai. Nobunaga’s decisive breakthrough on this flank changed the entire shape of the battle.

Scene 4 — The Oda Wheel Inward and the Azai Are Flanked

With the Asakura routed, the victorious Oda forces wheeled inward and struck the Azai from the flank and rear. Caught between the Tokugawa to their front and the Oda now threatening their flank, the Azai could no longer maintain their position. Nagamasa ordered a withdrawal, and the Azai-Asakura forces retreated.

Scene 5 — Aftermath and the Long War Continues

The Oda-Tokugawa alliance had won a clear tactical victory, but the Azai and Asakura were not destroyed. Both clans retreated to their castles and continued to resist. Nagamasa held out in Odani Castle until 1573, when Nobunaga besieged and took it; the Asakura clan fell in the same year. Anegawa thus opened the final chapter of the Azai-Asakura story — but it did not close it.

Why This Battle Matters Historically

1. The Oda-Tokugawa Alliance Proved in Battle

Anegawa was the first large-scale engagement fought by the Oda-Tokugawa alliance. The two forces coordinated effectively — Tokugawa holding the Azai while Oda broke through the Asakura and turned to help — demonstrating the alliance’s real military value. This partnership, forged in 1562 and tested at Anegawa, would prove one of the most consequential relationships of the entire Sengoku period, enduring until Nobunaga’s death in 1582.

2. The Human Cost of Nobunaga’s Ambition

Anegawa illustrates the brutal personal dimensions of Sengoku politics. Nobunaga fought his own brother-in-law. His sister Oichi, wife of Azai Nagamasa, would eventually be rescued after the fall of Odani Castle in 1573, but she had lived through years of war between her husband and her brother. After Nagamasa’s death, Oichi later married Shibata Katsuie, and died alongside him at the fall of Kitanosho Castle in 1583 — a life shaped entirely by the wars of the Sengoku era.

3. The Beginning of the Anti-Nobunaga League

The Azai-Asakura alliance was one piece of a larger anti-Nobunaga coalition that would later include the Takeda clan, the Ikko-ikki, and other powers. Anegawa was an early chapter in this long struggle. Nobunaga’s survival and victory here allowed him to continue his campaign toward national hegemony — but the opposition he faced would grow more formidable before it was finally broken.

List of Participating and Related Figures

Who were the key figures at the Battle of Anegawa? Below is a list of the main samurai and related figures already featured on this site.

Oda Side

Tokugawa Side

Azai-Asakura Side

  • Azai Nagamasa (浅井長政) — Lord of northern Ōmi; Nobunaga’s brother-in-law (husband of Oichi); commanded the Azai forces and survived the battle, holding out until the fall of Odani Castle in 1573
  • Asakura Kagetake (朝倉景健) — Commanded the Asakura forces at the battle on behalf of clan leader Asakura Yoshikage
  • Asakura Yoshikage (朝倉義景) — Head of the Asakura clan of Echizen; the clan fell in 1573

Final Thoughts

The Battle of Anegawa in 1570 was a pivotal engagement in Nobunaga’s long campaign to dominate central Japan. It demonstrated the strength of the Oda-Tokugawa alliance, revealed the personal costs that Sengoku ambition could exact, and set the stage for the final destruction of the Azai and Asakura clans three years later.

Victory at Anegawa did not end the threat — but it put Nobunaga firmly on the path toward doing so. In the brutal calculus of the Sengoku period, a wounded enemy still standing was a problem that had to be solved. It would take three more years and two more sieges before Nobunaga could finally move beyond the northern Ōmi threat and focus his attention on the wider stage of national unification.

Yanorisu
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