It was a short, two-week siege, fought between 13 and 27 September 1567, or in the Japanese calendar: from the 1st to 15th day of the eighth month, in the 10th year of the Eiroku era, according to the Nobunaga Chronicle.

[1] The siege ended in a decisive battle and victory for Nobunaga's combined forces, resulting in the subjugation of the Saitō clan, their vassals, and their allies.

In addition to these preparations, Tōkichirō devised and led a bold plan, something of a commando raid, to break into the castle and open the gates for the attacking army.

[7] At the time Tatsuoki was young but, as he attained adulthood, he was eventually considered incapable of effective leadership by his peers and retainers, viewed with contempt by his subordinates, and even despised by the local peasantry.

As a result, Nobunaga reasoned that Yoshitatsu's heir, Tatsuoki, likewise benefited from Dōsan's demise, and thus continued with his plans for invasion, using revenge as a pretext.

[6] The castle was situated atop Mount Inaba, which had a ruggedly steep northern face with the bank of the Sunomata River at its foot, and accessed by a winding avenue up the southern slopes.

[13] Although it was considered nearly impregnable,[14][15] Tatsuoki fled the parapets and hid within the castle while his retainers Takenaka Shigeharu (called Hanbei) and Andō Morinari commanded the defense.

[20] To this end, with support from Hachisuka Koroku, Kinoshita built Sunomata Castle on the bank of the Sai River opposite Saitō territory.

The clan headquarters and administrative center for Mino Province was Inabayama Castle, a mountain fortress atop Mount Inaba (in present-day Gifu city).

As Saitō Tatsuoki, the daimyo of the clan, had shown himself to be a cowardly and ineffective ruler, Takenaka Hanbei had staged a coup and took command of the castle and its garrison.

[12][27] As the troops assembled on the far shore, Nobunaga sent two messengers, Murai Sadakatsu and Shimada Hidemitsu, to three of the Saitō clan's top vassals, known as the Mino Triumvirate, asking for their cooperation in the upcoming battle.

[30] It is also certain that Kinoshita Hideyoshi devised a plan in which a small force would scale the north face of the mountain, enter the castle, and rush to open the gates for the besieging army.

[1] On the night of 26 September, Kinoshita gathered his team and, concerned over the late summer heat and the exertions in store, provided them with gourds of fresh water.

Horio Yoshiharu then guided Kinoshita Hideyoshi and the small assault force around to the back of the mountain, where they climbed the steep slopes by the light of a full moon.

[12][30] Sometime after dawn, Kinoshita's team infiltrated the castle, set fire to a storehouse and the powder magazine, and then rushed to open the front gates, cutting down whoever got in their way.

[12] With explosions erupting from the powder magazine and the other building burning fiercely, the castle defense quickly devolved into chaos, as the shocked and exhausted defenders thought they were under a full-scale attack from behind.

When Kinoshita's team had attained the gatehouse they tied their gourds to spears and waved them to their allies below to signal they were in position,[23] whereupon Kuroda's infantry charged the open gates and overran what was left of the castle's garrison.

[12] While Kuroda's men mopped up the last of the resistance, Kinoshita's team found a place to rest, while Horio Yoshiharu passed around a large gourd of sake he had taken from the castle's supply.

[1] In about two weeks' time Nobunaga had entered the sprawling Mino Province, raised an army, and conquered the ruling clan in their mountaintop castle.

[20] After the battle, Kinoshita was promoted in rank and made lord of three districts in the northern part of the newly conquered Mino province,[31] and not long afterward took the surname Hashiba.

When Nobunaga later gave him a field command, Hideyoshi used an image of a golden gourd as his battle standard in commemoration of his success at Inabayama Castle.