In 1567, Oda Nobunaga launched an attack on Mino Province from Sunomata Castle, led his forces across the Kiso River, and marched straight to the castle town of Inoguchi (now Gifu city) attracting the support of many Saito retainers along the way. Nobunaga laid siege to Inabayama Castle on 13 September. Even though the defenders were demoralized to see the banners of Saito retainers among the attacking army, the mountaintop castle was still in a nearly impregnable position. The siege took about two weeks. Near the end of the siege, Nobunaga's retainer Kinoshita Tōkichirō led a small party up the steep cliffs of Mount Kinka, entered the castle from the unguarded rear, and opened the front gates, allowing the attacking forces to enter. After Tatsuoki was defeated, Nobunaga claimed the castle and made it his primary base-of-operations.