was a Japanese samurai and daimyō of the late Sengoku period through early Edo period, who served the Tokugawa clan.
As one of the Tokugawa family's foremost military commanders, he was considered one of its "Four Guardian Kings" (shitennō 四天王) along with Sakai Tadatsugu, Honda Tadakatsu and Ii Naomasa. One of his most notable military accomplishments occurred during the Battle of Anegawa when he changed the tide of the battle with a flanking maneuver. He is also famous for conquering many Takeda clan castles in Tōtōmi Province from 1574-1579.
His court title during Toyotomi Hideyoshi's government was Shikibu-Shō (式部大輔).Nussbaum, Louis Frédéric et al. (2005). "Sakakibara Yasumasa" in ; n.b., Louis-Frédéric is pseudonym of Louis-Frédéric Nussbaum, see Deutsche Nationalbibliothek Authority File . During Tokugawa shogunate, he was appointed as Rōjū, or elder councilor.
Early life
Sakakibara Yasumasa was born in the year Tenmon-17 (1548), the second son of Sakakibara Nagamasa, in the Ueno district of Mikawa Province. The Sakakibara clan branch from which Yasumasa hailed, traditionally served the Sakai clan, a fudai clan whose lord was Sakai Tadanao, who was in turn a vassal of the Matsudaira clan. This classified the Sakaibara as baishin, or "rear vassals."
The young Yasumasa interacted with Matsudaira Motoyasu (later Tokugawa Ieyasu) often from a young age and was soon appointed as his page. Due to his valor at the Battle of Batogahara in 1564 against the Ikkō-ikki rebels in Mikawa, he was allowed to use the "yasu" from Motoyasu's name. From then on, he would use "Yasumasa" as his name.
In Eiroku-9 (1566), at age 19, Yasumasa had reached adulthood, and soon after, he and Honda Tadakatsu were appointed as hatamoto and each granted the command of 50 cavalrymen. From that point on, they would function as Ieyasu's unit commanders.
In 1568. Ieyasu was eager to expand eastward to Tōtōmi Province. Ieyasu and Takeda Shingen, the head of the Takeda clan in Kai Province, made an alliance for the purpose of conquering all the Imagawa territory. However, on January 8, 1569, the Takeda vassal Akiyama Nobutomo invaded the Tōtōmi province from Shinano Province. The Takeda clan, through Oda Nobunaga, with whom they had a friendly relationship, asked Ieyasu, who was Nobunaga's ally, to reconsider cooperation with the Takeda, but Ieyasu rejected the idea, and Ieyasu is considered to have been in a position of independence from Nobunaga to a certain extent. However, until around April of the first year of the Genki era, diplomatic negotiations were being conducted between Yasumasa and Tsuchiya Masatsugu, who acted as intermediaries between the two sides.
In 1570, Yasumasa fought at the Battle of Anegawa, he was in the second division, along with Honda Tadakatsu, who fought the Asakura Kagetake's left flank. After Tokugawa force was done dealing with Asakura force, they immediately dispatch Yasumasa and Honda Tadakatsu troops to assist Oda's forces who still struggling against the Azai army. Yasumasa and Tadakatsu struck the right flank of Azai Nagamasa's force, while subsequently followed with Inaba Yoshimichi on their track to flank Azai clan's left column, causing the Azai clan forces pushed back.
Later in 1573, He fought at the Battle of Mikatagahara, where he works together with Honda Tadakatsu fighting against a Takeda clan detachment led by Oyamada Masayuki, while Ishikawa Kazumasa covering the retreat of Ieyasu from the battle. Later in the same year Yasumasa and Honda Tadakatsu were tasked to capture the Nagashino Castle. Both of them manage subdue the castle from the Takeda clan. For the rest of the year service, he competed with Tadakatsu in capturing many of Takeda clan castles.
In 1575, During the conflict between Oda-Tokugawa alliance against Takeda Katsuyori, when the latter invaded Enshū province, Yasumasa and Honda Tadakatsu fought against Katsuyori, where they captured the Komyo castle in June. Later, Yasumasa also participate in the Battle of Nagashino when Oda-Tokugawa forces claimed victory against Katsuyori. Immediately after the Nagashino battle, he and Tadakatsu captured the Suwahara Castle, and was awarded by Ieyasu a famous sword which crafted by Takagi Sadamune. In July, Yasumasa and Osuga Yasutaka besieged the Koyama castle.
Later in 1581, Yasumasa stormed Tanaka castle which guarded by Takeda clan general named Ichijō Nobutatsu. In this battle, Yasumasa fought together with Matsudaira Ietada, Ii Naomasa, and Honda Tadakatsu, where they all managed to climb Tanaka castle wall and fought Nobutatsu's soldiers.
As head of Sakakibara clan
In 1579, Yasumasa was appointed to be the head of Sakakibara clan, succeeding his older brother, Sakakibara Kiyomasa. Kiyomasa decided to retire from his position after the incident of Matsudaira Nobuyasu who ordered to commit seppuku for treason accusation. Before his ascension to lead the Sakakibara clan, historical recorded the Yasumasa only commanded very few of Samurai warriors under him, with only one clan has been identified, which is the Takeo clan.
In 1581, Yasumasa participated in the Tokugawa army attack on Tanaka castle which guarded by Takeda clan general named Ichijō Nobutatsu. In this battle, Yasumasa, Matsudaira Ietada, Honda Tadakatsu, and Ii Naomasa, as they all climbed Tanaka castle wall and fought Nobutatsu's soldiers inside. In the same year, he also participated in the Siege of Takatenjin castle, where he took 41 enemy heads in combat.
In 1582, after the Honnō-ji Incident, Yasumasa accompanied Ieyasu in an arduous journey to escape the enemies of Nobunaga in Sakai and returning to Mikawa. However, their journey was very dangerous due to the existence of "Ochimusha-gari" groups across the route. The Ietada nikki journal has recorded that the escorts of Ieyasu has suffered around 200 casualties and only 34 person left when they finally arrived at Ietada residence in Mikawa.
Later in the same year, the Tenshō-Jingo war broke out between the Tokugawa clan and Hōjō clan in a contest to gain control of Shinano Province, Ueno region, and Kai Province Kai Province (currently Gunma Prefecture), which has been vacant since the destruction of Takeda clan and the death of Oda Nobunaga. Ieyasu lead an army of 8,000 soldiers entering Kai, Shinano Province, and Ueno, to annex it. However, the Hōjō clan in the Kantō region also led an army of 55,000 men and crossed the Usui Pass to invade Shinano Province. During this conflict, Yasumasa once stormed one of a castle belongs to the Hōjō, while Matsudaira Ietada harassing the Hōjō food supplies. Later, in the battle of Kurokoma, Yasumasa fought together with Okabe Motonobu and Mizuno Katsunari to repel the Hōjō army attempt to sneak into the rear of Tokugawa army.
In March of the same year, according to the Meishō genkō-roku record, after the destruction of the war against Hojo clan ended in truce, Ieyasu organized a kishōmon(blood oath) with many samurai clans that formerly were vassals of the Takeda clan assigned under the command of Tokugawa clan retainers.小宮山敏和「戦国大名家臣の徳川家臣化について 戦国大名武田家家臣を事例として」『論集きんせい』26号、2004年 Ieyasu Tokugawa planned to subduct the largest portions of former Takeda samurai under Naomasa's command, having consulted and reached agreement with Sakai Tadatsugu, a senior Tokugawa clan vassal. However, Ieyasu's decision garnered protest from Sakakibara Yasumasa, who went so far as to threaten Naomasa. Tadatsugu immediately defended the decision of Ieyasu in response and warned Yasumasa that if he did any harm to Naomasa, Tadatsugu himself would exact retribution by slaughtering the Sakakibara clan; thus, Yasumasa heeded Tadatsugu and did not protest further. Then Tokugawa decided assigned 70 members of former Takeda samurais from Tsuchiya clan under the command of Ii Naomasa. Meanwhile, Yasumasa himself received the command over 11 former Takeda samurai from Komai clan led by Komai Masanao, who later promoted as Hatamoto retainer of Yasumasa.柴辻俊六「武田家臣団の解体と徳川政権」『戦国大名領の研究』名著出版、1981年
Battle of Komaki-Nagakute In 1584, when Ieyasu chose to defy Toyotomi Hideyoshi, Yasumasa Ieyasu to serve in the campaign of Komaki and Nagakute. Yasumasa suggesting to Ieyasu that the region of Komaki would be suitable for the ensuing campaign. Then as a Toyotomi troops under command of Toyotomi Hidetsugu start entering the area of Komaki, Yasumasa join another Tokugawa general named Osuga Yasutaka to launch a surprise attack against unprepared Hidetsugu, where they inflicting heavy losses to Hidetsugu army. However, Yasumasa and Yasutaka advance were held back by reinforcement forces led by Hori Hidemasa, thus they retreat from the battle.
In the wake of the victory at Nagakute, Yasumasa circulated a derogatory manifesto proclamations which condemn Hideyoshi's conduct as betrayal towards the will of Oda Nobunaga and also insulting Hideyoshi's origin. This infuriated Hideyoshi, who later promised that he will reward of 100,000 Kan (Japanese gold ingot) to anyone who could bring him the head of Yasumasa.
Later in April, the front line in northern Owari reached stalemate. At this time, Kanie Castle was located about three miles between Ieyasu's Kiyosu Castle and Nobuo's Nagashima Castle, and was connected to the Mie moat and three castles: Ono Castle, Shimojima Castle, and Maeda Castle. At that time, Kanie castle were facing the sea and was one of the leading ports in Owari, along with Atsuta and Tsushima. Then in June 18, Ieyasu and Nobuo led 20,000 soldiers and besieged three castles: Kanie Castle, Maeda Castle, and Shimojima Castle. The Kanie castle were defended by Maeda Nagatane and Takigawa Kazumasu. Tadatsugu, Okanabe Mori, and Yamaguchi Shigemasa spearheading the attack towards Shimojima castle, while Sakakibara Yasumasa, Osuga Yasutaka were deployed to capture any fleeing defenders.
After the fall of Shimojima castle, On June 22, Oda Nobuo and Tokugawa Ieyasu launch an all-out attack on Kanie Castle. The soldiers led by Tadatsugu, who has been deployed at the major entrance, were exhausted after days of fierce fighting, and in the evening, the soldiers of Yasumasa Sakakibara and Ietada Matsudaira entered Kaimonjiguchi in their place. On June 23, Ieyasu entered the castle with Sakakibara Yasumasa, thus the castle were subdued.
Became famous as Tokugawa-Shitennō
On November 13, 1585, Ishikawa Kazumasa, senior vassal of the Tokugawa clan, defected from Ieyasu to Hideyoshi. This incident caused Ieyasu to undertake massive reforms of the structures of Tokugawa clan military government. At first, Ieyasu ordered Torii Mototada, who served as the county magistrate of Kai, to collect military laws, weapons, and military equipment from the time of Takeda Shingen and bring them to Hamamatsu Castle (Hamamatsu City, Shizuoka Prefecture). Later, he also appointed two former Takeda vassals, Naruse Masakazu and Okabe Masatsuna, as magistrates under authority of Ii Naomasa and Honda Tadakatsu, while he also ordered all of former Takeda vassals who now serve him to impart any military doctrines and structures they knew during their service under Takeda clan. Lastly, he ordered the three of his prime generals, the so-called "Tokugawa Four Heavenly Kings," Ii Naomasa, Honda Tadakatsu, and Sakakibara Yasumasa, to serve as supreme commanders of these new military regiments.
In 1586, according to "Sakakibara clan historical records", Ieyasu sent Yasumasa, Honda Tadakatsu, and Ii Naomasa as representatives to Kyoto, where three of them being regarded as "Tokugawa Sanketsu"(Three great nobles of Tokugawa). Then in following month, the three of them joined by Sakai Tadatsugu to accompany Ieyasu in his personal trip to Kyoto, where the four of them became famous as Tokugawa-Shitennō(Tokugawa's Four Guardians". Later, Yasumasa was given the title of "'Shikibu-shō'", when accompanying Ieyasu to Osaka to meet with Hideyoshi.