After a rocky start, Oda Nobunaga had finally secured his domain from domestic threats. While he had made an enemy of the Saitō Clan of Mino, they seemed content to despise him from afar. Unfortunately, the years of fighting and domestic uncertainty left Owari Province with a meager armed force of 3,000 men total. Once Nobunaga killed the region’s shugo, he also killed the military alliance he had signed with the Imagawa Clan. Imagawa Yoshimoto mustered 40,000* soldiers for a mission that would take them through Owari, and there is little doubt he planned to take Nobunaga’s head.
Before we dive into the battle proper, let’s briefly get to know Imagawa Yoshimoto. Nobunaga’s father, Nobuhide, was at least as ambitious as his son. He had bribed, threatened, and politicked his way to making the Oda Clan the de facto power in the region. When he died suddenly in 1551, Imagawa Yoshimoto wasted no time taking advantage. The very next year, he married his daughter to a scion of the mighty Clan Takeda to forge an alliance, and two years afterward arranged a marriage between his son and a princess of the Hōjō Clan. Thus he forged a mighty coalition composed of three major clans who were eager to expand their influence through intimidation and, if necessary, outright warfare. In 1560, having two years before charged his son Ujizane with the Clan’s political affairs, Yoshimoto raised a mighty army and decided it was time to march on Kyoto and take the title of Shōgun for himself. While he claimed that he was bringing this mighty army to aid the rapidly diminishing Ashikaga Shogunate, there can be no doubt of his intentions and ambitions. And as an added bonus, he would destroy an old rival Clan that happened to be in his path.
Had Yoshimoto succeeded in sweeping through Owari and brought his army to Kyoto, I think his chances of becoming Shōgun were very good. Japanese history would have likely taken a very different course, perhaps even opening itself to foreign ideas and influence far sooner. But although Yoshimoto commanded a massive army, he made an strategic error in his invasion of Owari that cost him his play for Shōgun, his power, and his very life.
It all started when one of Imagawa’s commanders, one Matsudairu Motoyasu (remember that name – he’s important!), stormed an Oda fort called Marune and took it by force, sending back seven heads to Yoshimoto with confirmation of his success. Yoshimoto took this as a good sign and pressed his army into Owari, committing their considerable unwieldy bulk to the sprawling highlands. They came to an area called Dengaku-hazama (Hazama means gorge), a narrow area where they decided to camp after news came that their advance forces had taken another Oda fort. Locals came to celebrate their success, bringing food and rice wine. A sudden windy rainstorm began suddenly just after midday and most of the soldiers fled to the shelter of their bivouac tents. When the rain finally relented, they emerged to see what looked like a massive army pitched against them on the high ground.
Their Arquebuses were drenched and useless, their weapons buried in wet mud. They tried in vain to mount a defense, but some feared that this new arrival was actually a rebellious contingent of their own army. Panic spread through the camp and most of Imagawa’s soldiers fled in terror, leaving their weapons and leader behind. Yoshimoto himself was still in his headquarters, demanding an explanation from his officers when the enemy arrived and overtook them. Yoshimoto was beheaded in the ensuing melee, perhaps before he even understood that it was Oda Nobunaga and his comparatively meager forces that had defeated him completely.
Nobunaga had been given two options by his retainers: resist the impending siege or surrender outright. In a blustery speech, he announced that he would do neither; he intended to go on the attack. Though he had perhaps 3,000 soldiers (and no reputable historian credits him with many more than that), he rejoiced to hear that Imagawa’s troops were camped in Dengaku-hazama as they celebrated their preliminary victories. As George Sansom puts it, “This was country over which he had roved as a boy, and he knew it well.” He knew that a narrow position like the foot of a gorge would mean that Imagawa’s troops couldn’t easily maneuver and could be trapped. He spread his troops wide and they waited through the rainstorm, keeping their weapons dry and ready for action. At his signal, they charged into the camp and made short work of the Imagawa troops, bringing their liege Yoshimoto’s head as a trophy.
The victory at Okehazama was a huge turning point for Nobunaga, and for the Oda Clan itself. This was a precarious time when weaker factions were eager to join with the strong; demonstrations of strength translated easily into political capital for established Clans. Nobunaga pressed this advantage – he made an alliance with the clever leader Matsudaira Motoyasu and his Clan and allied with the Takeda Clan through arranged marriage of an Oda princess to a Takeda prince. This left the younger Imagawa surrounded on all sides by hostile provinces, and so he fled to the neutral protection Hōjō Clan and later died in obscurity and exile. The Imagawa Clan died with him.
The Trouble With Mino
Mino Province was a thorn in Nobunaga’s side, an inauspicious failure in his early career as Daimyo when he tried to turn a longtime rival into an ally but aligned himself to the losing side of a family dispute and only compounded the enmity. In 1561, five years after Nobunaga had opposed him, Saitō Yoshitatsu died of a sudden illness and was succeeded by his son Tatsuoki. Sensing weakness, Nobunaga invaded Mino with 700 troops in 1561 and 1563, both times being dissuaded by the larger forces loyal to the Saitō Clan. In 1564, frustrated but practical, Nobunaga sent one of his favored retainers who had distinguished himself at Okehazama, Kinoshita Tōkichirō, to barter, promise, and outright bribe the Saitō Vassals to change their allegiance. By 1567, Nobunaga tried once more.
This time, everything hinged on Inabayama Castle. In his two previous attempts, warriors from western Mino had quickly assembled in numbers many times greater than his own, and so he withdrew. Thanks to the Oda Clan’s bribes and backroom deals, these warriors either stayed home or brought their warriors under Nobunaga’s banner instead. Within Inabayama Castle was Tatsuoki, the last scion of the Saitō Clan. Nobunaga’s troops built a fort (which eventually became a castle) across the river and Kinoshita Tōkichirō presented a bold plan.
Inabayama
On the evening of September 26, 1567, Nobunaga ordered a frontal assault on the castle’s south gate, forcing the meager garrison to engage in defense. Kinoshita Tōkichirō, meanwhile, had recruited six or seven men and led them through the surrounding forest to the steep mountain slope of Inabayama Castle’s north wall. It was a hard climb, and he gave each of his commandos a gourd of water for the hazardous climb, which took most of the night.
At dawn, the garrison was distracted with the main army’s assault, Tōkichirō and his men set fire to several buildings including a powder magazine which erupted terrifically and set much of the castle’s north side aflame. The defenders believed that there must be an assault underway and many of them rushed to the north only to be cut down by Tōkichirō and his commandos as they siezed control of the south gate and opened it, tying their water gourds to their spears and waving them as a signal for the Oda infantry to charge. The results were complete chaos within the castle and a decisive victory for Nobunaga. Inabayama was his.
Nobunaga’s Star Rises
The Mino Triumvirate, an alliance of three independent Daimyo in the province, immediately signed a permanent alliance with the Oda Clan afterward and there was no question that Nobunaga led the dominant superpower in the region. With his homeland and surrounding provinces more or less secure, Nobunaga could turn his attention to larger matters.
He renamed Inabayama Castle “Gifu,” which is the city’s name to this day. The Kanji for Gifu forms the same name as the mountain that famous general Wu Wang began his campaign to unify China centuries before, leaving little doubt to the extent of Nobunaga’s vast ambitions. And in case anyone did think it was just a coincidence, he also coined a new Clan motto: Tenka Fubu. Rule the Empire by Force of Arms.
*Some historians contend that Imagawa’s actual troop count was 25,000, and that 40,000 was just an exaggeration. A lot more soldiers than the 3,000 commanded by Nobunaga, in any case – JH