Sanada Masayuki (真田 安房守 昌幸, 1547 - July 13, 1611) was a Japanese lord and daimyō of the Sengoku period. He was the head of the Sanada clan, a regional house in Shinano province, which became a vassal of the Takeda clan in Kai province.
Along with his father and brothers, Masayuki served the Takeda clan during its heyday, when it was led by Takeda Shingen.
After his fall, Masayuki took over the leadership of his clan and, despite having little power, managed to establish himself as an independent daimyō under the Toyotomi regime through skillful political maneuvering in the midst of the powerful Tokugawa, Hojō and Uesugi clans.
Known for defeating the powerful Tokugawa army at the Battle of the Kami River and the Siege of Ueda, Masayuki is now considered one of the greatest military strategists of his time. In recent times, numerous portrayals in novels, films and other forms of media have helped to increase his popularity.
He was born the third son of Sanada Yukitaka in 1547, but the exact date is unknown. His childhood name was Gengorō (源五郎). When he was born, he was not allowed to succeed his father because of his two older brothers, Nobutsuna and Masateru.
In 1553, at the age of seven, he was sent as a hostage to the Takeda clan headquarters in Kai. There, he became part of the Okukinjūshū (奥近習衆), a group of six young servants close to Takeda Shingen.
According to the Kōyō Gunkan, Shingen favored him because he quickly recognized that Masayuki's talents and insight rivaled those of his father Yukitaka. As such, he was sometimes included among the Twenty-Four Generals, alongside his father and two older brothers.
In 1558, he became the adopted son of the Mutō family, a branch of the Ōi clan from which Shingen's mother descended, and adopted the name Mutō Kihei (武藤喜兵衛).
Towards 1564, he married Yamanote-dono (山手殿), a daughter of Uda Yoritada, who was a local lord of Tōtōmi Province. Later she gave birth to his two sons Nobuyuki and Nobushige. During this period, he participated in many battles under the Takeda clan, including the Fourth Battle of Kawanakajima (1561) and the Battle of Mimasetōge (1569).
Also most importantly, from 1572 onwards, he joined Shingen in his campaign towards Kyoto against the Oda and Tokugawa clans and took part in the Battle of Mikatagahara (1573).
In May 1573, Shingen died amidst his campaign and so Masayuki continued to serve his heir Takeda Katsuyori.
In 1574, his father Yukitaka died. At that point, his eldest brother Sanada Nobutsuna had already succeeded his father as the head of the Sanada clan.
However, during the disastrous Battle of Nagashino (1575) against the Oda clan, both his older brothers, Nobutsuna and Masateru, were killed, so he came back to Sanada clan and claimed his inheritance. In this, Masayuki supposedly had the support of Kōsaka Masanobu, who held Kaizu Castle in Northern Shinano and was also a chief retainer of the Takeda clan.
Katsuyori accepted his claim without any qualms.
In 1579, a year after Uesugi Kenshin's death, an alliance between the Takeda and Uesugi clans was established. The following year, ordered by Takeda Katsuyori, Masayuki invaded western Kōzuke, which was a Hojō domain at the time, and seized Numata Castle, putting it under control of the Takeda clan. The same year, he was appointed the title of Awa-no-kami (従五位下・安房守).
In 1581, he was ordered by Katsuyori to supervise the construction of the new Shinpu Castle at Nirasaki. In the same year, Numata Kageyoshi, former lord of Numata Castle, attempted to retake his old fief, but Masayuki schemed to assassinate him and thwarted his plans.
In April 1582, Oda and Tokugawa allied forces started an invasion of the Takeda territory. It is said that Masayuki had intended to shelter Katsuyori and advised him to abandon Kai Province and flee towards Sanada's domain in Kōzuke(Iwabitsu Castle).
Instead, Katsuyori decided to take shelter at Oyamada Nobushige's Iwadono Castle, but was betrayed and ultimately died at Tenmokuzan.
After the fall of the Takeda clan, Masayuki yielded to Oda Nobunaga and was put under the orders of one of Nobunaga's chief commanders, Takigawa Kazumasu. Masayuki managed to retain most of his domain, but had to abdicate Numata Castle to Takigawa Masushigue, Kazumasu's relative.
However, Nobunaga soon died at the Incident at Honnō-ji on June 21, 1582. Upon Nobunaga's death, Oda clan's grasp over former Takeda territories weakened. Amidst the chaos, Oda retainers who were assigned by Nobunaga to govern those territories, such as Mori Nagayoshi and Kawajiri Hidetaka amongst others, either fled or were killed by local insurrection.
Seeing this, neighboring Tokugawa, Hōjō and Uesugi clans all started to contest this vacuum of power in Shinano, Kōzuke and Kai provinces. This was called the Tenshō-Jingo Conflict.
On July 5, Takigawa Kazumasu lost decisively against the invading Hōjō army at the Battle of Kannagawa. In that occasion, Masayuki actually escorted back Kazumasu's remaining forces through Suwa, in Shinano.
Though, seeing this chance, Masayuki sent his uncle Yazawa Yoritsuna and took back Numata Castle. Also, he put his oldest son Nobuyuki in charge of Iwabitsu Castle, further reinforcing eastern Kōzuke.
On July 10, Uesugi Kagekatsu invaded Northern Shinano. Masayuki sided with the Uesugi initially, but a couple of weeks later he defected to Hōjō's side. Both Uesugi and Hojo's armies came to face each other at Kawanakajima on July 30, but direct combat was avoided as the Hōjō army turned back and advanced south towards Kai province, which was in turn invaded by Tokugawa forces.
Meanwhile, one of Uesugi clan's major retainer, Shibata Shigeie, revolted and Uesugi's forces also had to turn back from Northern Shinano to deal with it.
At one point, the Hōjō had come close to controlling most of Shinano province, but then in October, Masayuki suddenly betrayed them, providing help to Yoda Nobushige, a local lord who had been resisting against Hōjō's advances under the Tokugawa banner at Kasuga Castle.
He then officially defected to the Tokugawa's side. Faced with this development, Hōjō Ujinao saw his position in the conflict weaken and decided for a peace treaty and further alliance with the Tokugawa clan. This event marked the end of the conflict which lasted for roughly 5 months after Nobunaga's death. Masayuki was now a vassal of Tokugawa Ieyasu.
In 1583, Masayuki started the construction of Ueda Castle and the surrounding town. It became the headquarters of the Sanada clan in the following years.
In 1584, Tokugawa Ieyasu lead his army west towards Owari province in the Battle of Komaki and Nagakute against Hashiba Hideyoshi. Masayuki was left in northern Shinano to keep the Uesugi clan in check and took this opportunity to subjugate small, neighboring landlords and consolidate his power in the region.
In December, as Ieyasu made peace with Hideyoshi and returned to his territory, he was pressed by Hōjō Ujinao to act on the terms of their treaty. In 1585, Masayuki moved their main bastion from Sanada-shi Yakata to Ueda Castle.
In that treaty, among other terms, Tokugawa Ieyasu agreed to transfer Numata Castle and its adjacent lands in Kōzuke province to the Hōjō clan. In April 1585, Ieyasu advanced his army into Kai province in a move to pressure Masayuki into abdicating Numata Castle. Masayuki however, resisted having to hand it over, having conquered it with great effort years before.
Ultimately, he decided to cut relations with Tokugawa Ieyasu and once more switched allegiances by sending his second son Nobushige to Uesugi Kagekatsu as a hostage. With this move, he effectively joined Hashiba Hideyoshi's side, which opposed the Tokugawa-Hōjō alliance.
Months later, Tokugawa forces invaded Sanada clan's territory in northern Shinano province with 7,000 men and laid siege to Ueda Castle, which was defended by only 1,200 soldiers. However, Masayuki was able to inflict 1,300 casualties on Tokugawa's side and won a decisive victory.
Meanwhile, Hōjō Ujinao attacked Numata Castle, but was also rebuffed by Sanada forces. This was the First Battle of Ueda Castle, a victory that earned Masayuki national prominence. Following this, Masayuki went from being just a former Takeda retainer to become recognized as an independent daimyō.
Following his victory over the Tokugawa clan, Masayuki became a vassal to Toyotomi Hideyoshi. In doing so, he sent his son Nobushige (at the time a hostage to Uesugi clan) as a hostage to Osaka.
In 1586, the Hōjō clan try to take Numata Castle once more, but again are repelled. Tokugawa forces also gather and march towards Ueda Castle again, but Toyotomi Hideyoshi interposes. At this point, Hideyoshi's political presence in Japan is too strong for the Tokugawa clan to oppose, and at his mediation, the attack is called off.
However, he also designates Masayuki as a back-up power to the bigger Tokugawa forces in the region. This effectively means that Masayuki now responds to Tokugawa Ieyasu in all military matters.
The following year, 1587, sees Masayuki travelling to Sunpu to meet with Tokugawa Ieyasu. Then, he goes to Osaka to be received in audience by Toyotomi Hideyoshi, and thus formally become a vassal of the Toyotomi regime.
Two more years would pass until the dispute between the Sanada and Hōjō clans involving Numata Castle and adjacent areas would be mediated by Hideyoshi and resolved. In 1589, Hideyoshi decides the Sanada clan would relinquish all of its domain east of Tone River, including Numata Castle, to the Hōjō clan.
In turn, he granted them some territory in southern Shinano. However, by the end of that year, Inomata Kuninori, a retainer from the Hōjō clan who was now holding Numata Castle, is deceived into attacking the nearby Nagurumi Castle, located west of Tone River and defended by Sanada forces.
The attack is successful and the castle is seized by Hōjō forces, but by this time, Toyotomi Hideyoshi had sanctioned a rule which prohibited daimyōs from engaging in battle over private disputes. This incident fully breached this rule and it would go on to become the reason of the Siege of Odawara in 1590, and the subsequent fall of the Hōjō clan.
After Hideyoshi's death in 1598, Masayuki joined Ishida Mitsunari's side during the Battle of Sekigahara. Masayuki sent his eldest son, Nobuyuki, to the eastern side, while Masayuki and his younger son, Nobushige, fought on the western side, a move that ensured the Sanada clan's survival.
Fortifying Ueda Castle, Masayuki fought against Tokugawa Hidetada's 38,000 men with only 2,000 soldiers. This was the Second Battle of Ueda Castle, and, whilst it was not exactly a victory, Masayuki was able to deliver a heavy blow to Hidetada and delay his forces for long enough that they were unable to show up at the main battlefield on time.
However, the western side, led by Ishida Mitsunari, lost the main battle, and the victorious Tokugawa Ieyasu was able to redistribute fiefs at will. Masayuki and Nobushige were initially going to be executed, but, given Nobuyuki's participation in the eastern army, they were instead exiled to Kudoyama in Kii province. The Sanada clan was inherited by Sanada Nobuyuki.
Sanada Masayuki died of an illness in Kudoyama in 1611.
Even though Masayuki was never able to expand his territories as well as other daimyōs, he is nevertheless often considered a talented daimyō, doomed by misfortune and the inconvenient terrains which surrounded his home domain.
Toyotomi Hideyoshi had called Masayuki a person whose inside did not match his outside, that his allegiance was fickle and not to be trusted. Nevertheless, it was exactly his drifting alliances that helped the Sanada clan survive the onslaught of hostile clans, and, since the Edo period, he has been more extolled than vilified.