Just when Oda Nobunaga desperately needed a breakthrough, a bridge quietly emerged: Mizuno Nobumoto took the initiative to broker a bridge between the Oda and Matsudaira clans. Nobunaga seized this opportunity with utmost sincerity, marrying his daughter to the son of Matsudaira Motoyasu, forging a strong alliance through this marriage. From then on, Matsudaira Motoyasu and the Imagawa clan fell out completely. To sever any last ties with his former master, he avoided the character "moto" in Imagawa Yoshimoto's name and changed his name to Matsudaira Ieyasu. Thus, an alliance that would later influence the world was quietly forged.
With his eastern front secured, Nobunaga turned his attention westward to Mino. His father-in-law, Saito Dosan, known as the "Viper," had long since perished in a strife with his son, Saito Yoshitatsu (originally named Shinkuro). Hoisting the banner of revenge for his father-in-law, Nobunaga launched numerous campaigns against the patricide and fratricide, but to no avail.
When Saito Yoshitatsu's son, Saito Tatsuoki, ascended the throne, Nobunaga again launched his campaign against Mino. He forced a crossing of the Sumomata River and engaged Tatsuoki's army at Jushijo, resulting in a stalemate and ultimately a retreat. Saito's powerful general, Hayato I, was like a nail firmly pinned to the Sumomata region, repeatedly frustrating Nobunaga's advances.
Faced with this impenetrable fortress, Nobunaga decisively changed his strategy. He made a bold decision: to relocate his base from Kiyosu Castle to the more forward Komaki. This location offered convenient transportation, led directly to the heart of Mino, and was lightly defended. This move dramatically transformed the situation: Inuyama Castle, which had long been in cahoots with the Saito clan, surrendered, and the defenders of Okuchi Castle collapsed without a fight. Nobunaga capitalized on this opportunity by dispatching generals such as Niwa Nagahide to capture several castles in quick succession, advancing directly towards the heart of Mino.
Saito Tatsuoki, seeing the situation as dire, personally led his army to besiege Kajita Castle. Upon hearing the news, Nobunaga immediately rushed to its aid. In this crucial battle, he finally defeated the enemy general, Hayato Masaru, who had been a real headache for him.
However, western Mino remained a formidable challenge. Nobunaga repeatedly attacked, but all efforts were fruitless. After much deliberation, he devised a brilliant plan: to build an outpost fortress at Sumomatari, deep within enemy territory! This would be like handing a knife into the enemy's hands, a move that would put the defender at risk of certain death.
At this point, a young general named Kinoshita Tokichirō volunteered. He gathered refugees, offering them food and shelter, and miraculously built Sumomatari Castle right under the enemy's noses. Saito Tatsuoki launched repeated attacks, but each time, Tokichirō's extraordinary bravery and strategy repelled them. Not only was Tokichirō skilled at defense, but he also mastered psychological warfare, skillfully employing tactics to sow dissension and unsettle the Mino generals.
Meanwhile, Saito Tatsuoki was undermining his own defenses. He indulged in alcohol and sex, neglected state affairs, and was arrogant and rude to his retainers. Disheartened, key officials like Iyo no Kami Inaba, Ujiie Bokuzen, and Andō Iga no Kami secretly contacted Oda Nobunaga, offering to act as accomplices.
With both internal and external conditions ripe, Nobunaga finally launched his decisive attack. He feigned a massive attack on Mikawa, but, taking advantage of the Saito clan's moment of complacency, he launched a lightning-fast assault on Inabayama Castle, the heart of Mino!
Thus began a battle that would determine Mino's fate. Fierce generals like Shibata Katsuie and Sakuma Nobumori led a fierce assault, with Nobunaga personally overseeing the battle. Taking advantage of the defenders' panic, the Oda army set fire to the inner city. A strong fire, fueled by the wind, instantly reduced the castle town to scorched earth. Nobunaga seized the opportunity to surround Inabayama Castle, cutting off all external access.
Desperate, Saito Tatsuoki was forced to feign surrender and then flee in panic. This defeated general suffered a tragic fate. First rejected by the Settsu Miyoshi clan, he ultimately defected to the Echizen Asakura clan, where he was killed fighting for them. Thus ended the once-powerful Saito clan.
After defeating his formidable enemy, Oda Nobunaga relocated his center of government to this strategic location. He renamed Inabayama Castle the ambitious "Gifu Castle," inspired by the Zhou Dynasty King Wen's "Phoenix Crying at Mount Qishan," pacifying the world. From this vantage point, he commanded a westward march, his grand ambitions for dominance slowly unfolding.