Date(s): June 1560, exact date unknown

Armies: Oda Army vs. Imagawa Army

Victor: Oda Army

Casualties: Exact number for each sides unknown

The Battle of Okehazama was a clash between the Oda and Imagawa clans which ended with the fall of the Imagawa clan and the rise of the Oda, more importantly, the rise of Oda Nobunaga. It is the beginning of the era of the Three Unifiers and all three of the participated in the battle. The battle was the conclusion of Imagawa Yoshimoto’s march to Kyōto.

Before the Battle

The Battle of Okehazama was the end of Imagawa Yoshimoto’s march to the capital, a march that began in 1558. The Imagawa clan was one of the most powerful clans in Japan, and could tie their lineage to the famous Taira clan from the Gempei War (1180-1185). Yoshimoto’s fief of Suraga was near Oda Nobunaga’s fief of Owari, and the rivalry between the two clans was a fierce one.
By 1558, Imagawa Yoshimoto decided to march to Kyōto to take over the capital and take the title of shōgun. To do this, he decided to take out as many as the regional daimyo as he could along the way, and he set his sights on Owari. He began attacking Oda’s fortresses along the Owari/Mikawa border. One of the first sieges that took place was the siege of Terabe. This was Tokugawa Ieyasu’s first battle and it was a success. Serving on the side of the Imagawa, Ieyasu attacked the fortress after the keeper, Suzuki Shigeteru, defected from the Imagawa to the Oda. Not only did Ieyasu take Terabe, but he also repelled the reinforcements Nobunaga sent to help Suzuki. The following year, Ieyasu was able to get much needed supplies to the Imagawa fort of Odaka while being besieged by the Oda Army. It was the fall of Washizu and Marune in 1560 that set the battle of Okehazama into motion.

The Battle

Oda Nobunaga was at Kiyosu Castle when he got the news that the Oda fortresses if Washizu and Marune had fallen into the hands of the Imagawa and Yoshimoto’s Army of 25,000 was marching further into Owari, however, they were resting in a wooded gorge called Dengaku-hazama, an area Nobunaga knew well from childhood. He had two options to consider: either wait for a siege of Kiyosu Castle or attack the army head-on. Nobunaga’s retainers urged him to take the defensive. Despite their urging, Nobunaga made the decision to attack the Imagawa Army, a decision that was seen as suicidal by his retainers. Nobunaga managed to gather 2,500 men, one of them being Toyotomi Hideyoshi: his first battle.
Oda Nobunaga took up position at Zenshōji, near the Imagawa fort of Narumi and close to Dengaku-hazama. He sent out scouts and learned that the Imagawa Army were celebrating their recent victories in the gorge, many of the soldiers and generals were drunk or napping. Nobunaga planned for a surprise attack, first creating a fake army at Zenshōji then moving slowly toward the Imagawa encampment. Due to the hot and humid day, a thunderstorm broke out, giving Nobunaga the perfect cover to move closer and into position for the attack. As the rain broke, Nobunaga and his army attacked.
The Imagawa Army panicked. Many were drunk and could not fight, while those ran for the hills because they were so scared. Imagawa Yoshimoto was napping at the time, and woke up because of the commotion. Thinking that it was his own army fighting because of their recent drunken celebrations, he stepped out of his tent to tell them to be quiet. He was met with an Oda soldier stabbing him with a spear. Before Yoshimoto could draw his sword, another Oda soldier beheaded him. The rest of the army scattered after the loss of their leader.

The Aftermath

Grave of Imagawa Yoshimoto at Nagoya near Okehazama

The battle ended with Oda Nobunaga completely destroying the Imagawa clan. It is unclear on the casualties of this battle but it is recorded that, at least on the Imagawa side, all but two senior officers were killed. Oda Nobunaga became a force to be reckoned with, something which Tokugawa Ieyasu realized, thus becoming allies with Nobunaga. Okehazama set the stage for unification in Japan, beginning with Oda Nobunaga. Today, the battlefield is a park, and it contains the grave of Imagawa Yoshimoto, marking the spot where he was killed. Though the battlefield is actually Dengaku-hazama, the battle is named after the nearby village of Okehazama.