The Sanada clan began with Sanada Yukitaka, one of the "Twenty-Four Generals of Takeda", and became a Shinano clan with a heavy takeda shingen, but that was all, and as far as Japan as a whole was concerned, the Sanada clan could only be regarded as a small clan. In the era of chaotic war, the big Hao clan is precarious, not to mention the small Hao clan, in order to survive, for the continuation of the clan, many small Hao clan will survive by separating the family.
After the death of Sanada Yukitaka, his eldest son Sanada Nobunaga and his second son Sanada Masahiro died in the Battle of Nagashiro, so the third son, Sanada Masayuki, appeared on the stage of history, this Sanada Masayuki was not only brave and skilled, but also wise, but unfortunately at this time, the world has become a general trend, and it is almost impossible to become a daimyō through the way of "Shimo Kagami", at least Sanada Masayuki does not have this opportunity.
After the fall of the Takeda clan, he returned to the Shun Oda clan and incorporated it into the Kwantung general Kazuyoshi Takikawa; after the honnō-ji rebellion, Takikawa Kazuyoshi was defeated by the Hojo clan, and Sanada Masayuki immediately returned to the Hojo clan; but when the Hojo clan's army continued to attack north, threatening the Sanada clan, Sanada Masayuki immediately betrayed the Hojo clan, turned to Tokugawa Ieyasu, and sent his eldest son Sanada Nobuyuki to Tokugawa Ieyasu as a hostage.
However, Tokugawa Ieyasu did not look up to Sanada Masayuki too much, but instead asked Sanada Masayuki to give up one of his castles to the Hojo clan, Sanada Masayuki of course could not bear it, so he immediately turned to Uesugi Keikatsu, sent his second son Sanada Keisuke to Uesugi Keikatsu as a hostage, and began to strengthen the city wall; this caused Tokugawa Ieyasu and Hojo clan Naoru to be extremely dissatisfied, Andogawa Ieyasu even sent troops to attack Sanada Masayuki, but was unexpectedly defeated by Sanada Masayuki.
Later, Uesugi Keikatsu returned to Shuntomo Hideyoshi, and Sanada Masayuki, who was obedient to the Uesugi family, also indirectly became a member of the Toyotomi Group and was protected by it. Toyotomi Hideyoshi also attached great importance to Sanada Masayuki, so he personally intervened to mediate the conflict between Sanada Masayuki and Hojo Clan Nao. Originally, this was the end of the matter, but the Hojo clan was greedy enough to send his men to rob Sanada Masayuki's castle, and Toyotomi Hideyoshi launched the Battle of Odawara and destroyed the Hojo clan.
As a result, Sanada Masayuki and Sanada Yukimura were loyal to Toyotomi Hideyoshi, but the key point of everything occurred after Toyotomi Hideyoshi's death; shortly after Toyotomi Hideyoshi's death, Ishida Sansei, who represented the Toyotomi clan, and Tokugawa Ieyasu raised an army, Sanada Masayuki sent a secret letter to the eldest son, Sanada Nobuyuki, and after the father and son met, Sanada Masayuki and his second son Sanada Yukimura joined Ishida's Western Army, and the eldest son, Sanada Nobuyuki, joined Tokugawa Ieyasu's eastern army.
The reason given is very grandiose, because Sanada Masayuki's wife is the sister of Ishida Sansei's wife, Sanada Yukimura's wife is the daughter of Otani Yoshiji, Ishida Sansei is the leader of the Western Army, and Otani Yoshiji is also an important figure in the Western Army, so it seems reasonable for these two people to join the Western Army. Sanada Nobuyuki was the son-in-law of Tokugawa Ieyasu's number one general, Honda Tadatsukatsu, so it was natural to join the Eastern Army.
Of course, some people believe that this result is the embodiment of Sanada Masayuki's political skills, because in this way, whether the Eastern Army or the Western Army wins, the Sanada family will be saved. In fact, during the Sekigahara War, the performance of Sanada Masayuki and Sanada Yukimura made Tokugawa Ieyasu hate them to the bone, but after the war, due to the persuasion of Sanada Nobuyuki and Honda Tadatsukatsu and Ii Naomasa, the idea of executing these two was eliminated, and they were only exiled.
Many people believe that this is Sanada Nobuyuki's "show", which may be partly due to it, but more often than not, he still does not want to see his father and brother killed, and Tokugawa Ieyasu also admires Sanada Nobuyuki's heavy and righteous side, and with a wave of his hand, he seals the 95,000-stone territory of Sanada Nobuyuki, including the 38,000 stones owned by the Sanada family for generations. However, during the Osaka Winter Front and the Osaka Summer Front, it is estimated that Tokugawa Ieyasu regretted his original decision.
Because Sanada Yukimura's bravery and intelligence are not inferior to his father's, and even won, it can be said that the Osaka Winter Formation is Sanada Yukimura's personal performance stage. Later, in the Osaka Summer Front, Sanada Yukimura led a cavalry regiment directly to Tokugawa Ieyasu Honjin, intending to kill Tokugawa Ieyasu, Tokugawa Ieyasu's army had no enemy, if it were not for Tokugawa Ieyasu's order to put down the flag when he fled, so that Sanada Yukimura could not find his position, perhaps the history of Japan would have been changed again.
However, this kind of raid was fought quickly, and eventually Sanada Yukimura fell under siege, and although Sanada Yukimura escaped when he was wounded by multiple gunshots and exhausted, he was unable to return to heaven and was later killed. Although Sanada Yukimura was killed in battle, his heroic deeds and glorious image have become the topic of many literary scholars, not only known as "Japan's first soldier", but also listed with Genyoshi Kei and Nanki Masanari as the "three last tragic heroes" in Japanese history, which can also be regarded as a famous name in the history of Japan.
As for Sanada Nobuyuki, he was also highly regarded as a master architect after the war, and later Tokugawa Hidetada moved his seal and added 35,000 stone domains to him, with a total territory of 130,000, becoming the daimyō of the Matsushiro Domain of Shinano Province. Although Sanada Nobuyuki experienced many ups and downs in the matter of heirs, it was passed down until the Meiji Restoration, when the tenth generation of heirs, Sanada Yukimin, was removed from the domain, and this Sanada Yukimin was finally awarded the title of count, which is not bad.