Siege of Inabayama Castle The of 1567 was the final battle in Oda Nobunaga ' s campaign to defeat the Saitō clan in their mountaintop castle and conquer Mino Province , Japan . 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 8th month , in the 10th year of the Eiroku era , according to the " Nobunaga Chronicle " . The siege ended in a decisive battle and victory of Nobunaga ' s combined forces , and resulted in the subjugation of the Saitō clan , their vassals , and allies . This victory was the culmination of Nobunaga ' s Mino campaign , waged intermittently over the previous six years , and brought an end to a rivalry between the Oda clan of Owari province and the Saitō clan of Mino , which began over twenty years earlier between Nobunaga ' s father , Oda Nobuhide and Saitō Dōsan . Due to the weak leadership of the Saitō , many samurai leaders defected to Nobunaga before the battle , while others willingly submitted afterward . With this victory , Nobunaga took control of the expansive and fertile Mino Province and gained numerous supporters and resources . Nobunaga had the former Saitō castle repaired and renamed it Gifu Castle , a firm base from which to expand north into the Hokuriku region and to make his drive toward Kyoto . Gifu Castle functioned as his primary residence and military headquarters until he moved to the partially completed Azuchi Castle in 1575 . Nobunaga ' s young retainer Kinoshita Tōkichirō ( later known as Toyotomi Hideyoshi ) played an important role in attaining the victory at Inabayama . In the years leading to the battle , he negotiated for the support of local warlords , which ensured a ready - made army by the time of the attack , and built a castle on the edge of the enemy ' s territory to serve as a staging point for the attack . 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 . As a result of his efforts and the victory , his standing with Nobunaga rose considerably . Thus , in addition to the battle ' s immediate importance to Nobunaga ' s plans , it was also an important step in Toyotomi Hideyoshi ' s rise to power . Background . In 1549 young Oda Nobunaga ( 1534 – 1582 ) , who would later become a major daimyo of Owari province , Japan and would initiate the unification of 16th century Japan , was married to Nōhime , the daughter of Saitō Dōsan , leader of the rival Saitō clan of neighboring Mino Province . Nobunaga was the second son of Oda Nobuhide , head of the Oda clan , who was at that time fending off opponents on the northern and eastern borders of Owari province , matters that were complicated by internal dissent . Saitō Dōsan , lord of Mino , was a strong and ruthless leader , but internal strife had begun to split the Saitō into factions . Both clans needed some respite to deal with more pressing problems and thus the political marriage of Nobunaga and Nōhime brought an end to the clans ' rivalry and their border skirmishes . In 1555 Saitō Yoshitatsu , eldest son of Dōsan , came to believe his inheritance would be taken away and murdered his two younger brothers . The following year he rallied troops loyal to him and openly rebelled against his father . Dōsan indeed changed his will and named his son - in - law , Oda Nobunaga , his legal heir . Shortly thereafter Dōsan was killed by one of Yoshitatsu ' s retainers at the Battle of Nagaragawa . At the time Nobunaga was not in a position to help his father - in - law and the Saitō civil war soon ended before any active intervention could be mounted . In 1561 Yoshitatsu died of leprosy and his son , Saitō Tatsuoki , succeeded to the leadership of the clan . 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 . After the Oda and Matsudaira clan s allied and then defeated the Imagawa clan at the 1560 Battle of Okehazama , Nobunaga was in a more secure position to focus on their northern neighbor , the Saitō clan . Nobunaga ' s plans for an invasion of Mino were ostensibly motivated by revenge for the death of his father - in - law , Saitō Dōsan , but Yoshitatsu died before Nobunaga could attack . 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 . Mino campaign . Oda Nobunaga mounted forays into Mino territory in 1561 and 1563 , which resulted in brief battles . In each expedition Nobunaga and his 700 troops were outnumbered by rapidly assembled forces under local daimyo , who would muster up to 3 , 000 men . Caught in the open and unable to organize a defense , he fell back each time to his home territory . The local history of Gifu city states that in 1564 Nobunaga went so far as to attack Inabayama Castle , the headquarters of the Saitō clan . 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 . Although it was considered nearly impregnable , Tatsuoki fled the parapet s and hid within the castle while his retainers Takenaka Shigeharu ( called Hanbei ) and Andō Morinari commanded the defense . Nobunaga then left or was driven out soon afterward . In later years Nobunaga had this setback expunged from records and omitted from the " Nobunaga Chronicles " . Starting in 1564 , Oda Nobunaga began dispatching his loyal retainer , Kinoshita Tōkichirō , to convince , with liberal bribery , many of the warlords in the Mino area to defect to the growing alliance under the Oda clan . Kinoshita even approached Takenaka Hanbei , who was considered a brilliant strategist but lived in pious seclusion , to persuade him to defect . Although the Saitō retainer was frustrated by the ignominious behavior of Tatsuoki , he did not want to appear capricious with his loyalty , and declined Kinoshita ' s offers on behalf of his lord . Kinoshita was impressed with the integrity of the retainer and invited him to an extended stay in his home , as a guest . Hanbei admitted that the Saitō clan could not survive for much longer under Tatsuoki , and accepted Kinoshita ' s invitation in exchange for a promise of leniency if ever the Saitō leadership fell into Kinoshita ' s hands . In 1566 , in anticipation of the upcoming campaign , Kinoshita proposed that a castle should be built somewhere near Inabayama Castle to serve as a staging point for the Oda forces . Nobunaga agreed and charged Kinoshita with the task . To this end Kinoshita built Sunomata Castle on the bank of the Sai River opposite Saitō territory . The advantage of the castle ' s proximity to the enemy was also a problem during construction . Until the castle was complete , Kinoshita ' s men and the construction site were vulnerable to an amphibious attack from across the river . According to legend , Kinoshita built the castle in one night ; however it is more likely that it was the tower ' s skeleton with a facade that was seen from the opposite bank . The result of the hasty construction was meant to give his own men a vantage point and to surprise and impress the enemy . Stalled by the enemy ' s caution , Kinoshita ' s men were able to quickly transform the fragile framework into a functioning fortification , and then into a complete castle . Nobunaga then ordered Kinoshita to remain as steward of the castle , and bestowed upon him the name " Hideyoshi " . Siege . In 1567 , Oda Nobunaga led an attack against the Saitō clan of Mino Province . 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 . Although Tatsuoki was allowed to remain the titular head of the clan , he contributed nothing to the outcome of the battle . When the Oda army entered Mino , Hanbei prepared the garrison for the defense of the castle . According to the " Shinchō kōki " ( or " The Nobunaga Chronicles " ) , preparations for the battle began on 13 September 1567 ( Eiroku - 10 year , 8 - month , 1 - day ) . Nobunaga entered the area , made contact with allies , and the core of Nobunaga ' s army of about 5 , 000 troops crossed the Kiso River . 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 . Mino warlords that Kinoshita Hideyoshi had persuaded to defect brought additional troops to Nobunaga ' s banner . As the forces loyal to Nobunaga moved across the plain , several skirmishes were fought in a futile effort to turn the invading forces . Nobunaga ' s forces then entered the town of Inoguchi , which lay below Inabayama Castle . To clear the field of view and provide space for the besieging army , Kinoshita Hideyoshi ' s vanguard set fire to the town . As some soldiers took positions on Mount Inoguchi and a nearby ridgeline , the main army positioned itself before Mount Inaba to begin the siege . The greatly augmented army , now bristling with the flags of the Saitō clan ' s former vassals and allies , bewildered the castle ' s defenders . During the days that followed , Kinoshita dispatched men to gather intelligence , especially from peasants willing to help . Kinoshita met with a local resident , Horio Yoshiharu , who showed him a little - known path that led up the north slope of the mountain . The north slopes below the castle were so steep that assault by a large force was considered impossible , and was thus effectively ignored by the defenders at the advent of battle . Final assault . It is uncertain exactly what happened on the battlefield between 14 – 25 September . Given what is known of Nobunaga ' s aggressive fighting style , the prevailing siege tactics of the day , the layout of the Japanese castle , and the events that followed , it can be inferred that Nobunaga ' s forces pressed their attack and probably breached the outer defenses of Inabayama Castle . It is known , however , that Kuroda Kanbei , considered a talented strategist , was charged with directing and coordinating the main attack . 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 . Nobunaga approved and charged Kinoshita with leading the raid . For his team Kinoshita selected Horio Yoshiharu , Hachisuka Koroku , and five or six other men to accompany him . On 26 September Nobunaga was so confident of Kinoshita ' s plan and the outcome of the battle that he had an heraldic partition erected on the battlefield where he held a meeting with his top officers and allotted tasks pertaining to the re - construction of the castle following the battle . He also greeted the daimyo of the Mino Triumvirate , who were stunned by his audacity , and offered them sake . 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 gourd s 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 . At dawn , while Kinoshita ' s mission was in progress , the main force under Kuroda Kanbei proceeded with its attack on the castle . 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 whomever got in their way . 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 . Kinoshita ' s men , filthy from the night ' s exertions and brandishing bloody swords as they rushed across the main courtyard , added to the impression . The castle garrison was thrown into complete disarray as men were pulled from the parapet s to face the nonexistent assault , while others threw down their weapons and surrendered . 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 , whereupon Kuroda ' s infantry charged the open gates and overran what was left of the castle ' s garrison . 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 . By the end of 27 September 1567 Inabayama Castle had fallen and the remaining lords of Mino province formally surrendered to Nobunaga . Aftermath . In about two weeks ' time Nobunaga had entered the sprawling Mino Province , raised an army , and conquered the ruling clan in their mountaintop castle . Following the battle the Mino Triumvirate , awed by the speed and skill of Nobunaga ' s conquest , permanently allied themselves to Nobunaga . Nobunaga had the castle repaired and renamed it Gifu Castle . The castle - town of Inoguchi was likewise renamed Gifu , after the mountain from which Wu Wang launched his campaign to unify China . Nobunaga had a lavish manor built at the base of the castle mountain . He then transferred his primary base and residence from Komaki Castle to Gifu , from which he would launch his historic march on Kyoto the following year . He continued to use Gifu Castle as his primary residence and headquarters until he moved into the partially completed Azuchi Castle in 1575 . Saitō Tatsuoki survived the battle , though there are at least two accounts of how he managed this . In one account , Tatsuoki abandoned the castle the night before the final attack , took a boat , and fled down the Sunomata River . In another account , following the breach of the main gate , Hideyoshi dispatched a messenger to the main tower , where Tatsuoki and his entourage were cornered , with assurances of leniency if the Saitō holdouts would surrender . Tatsuoki accepted the offer and , with Nobunaga ' s troops forming two lines , Tatsuoki marched out of the main tower with his family and retinue . In any event , Tatsuoki eventually found his way to Nagashima , Ise Province . He lived in exile for a while , but eventually sought refuge with Asakura Yoshikage . He was killed in the Battle of Tonezaka , at the age of 26 , in 1573 . The efforts of Kinoshita Hideyoshi as the mastermind of the victory were recognized by Nobunaga and his status rose accordingly . After the battle Kinoshita was promoted in rank and made lord of three districts in the northern part of the newly conquered Mino province , 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 . In time he would change his surname again , to " Toyotomi " . Kuroda Kanbei , who led the frontal attack , and Takenaka Hanbei , who directed the castle ' s defense , would both eventually serve Toyotomi Hideyoshi . Order of battle . At the outset of the siege , Nobunaga organized the troops of his allies and retainers into several divisions , with a reserve and a vanguard :