真田氏
In 1600, before the Battle of Sekigahara, Tokugawa Ieyasu rallied various "daimyōs" to attack Uesugi Kagekatsu. The Sanada clan complied as well, but when Ishida Mitsunari decided to challenge Ieyasu, Masayuki and Yukimura joined the western forces, parting ways with Masayuki's eldest son and Yukimura's brother, Nobuyuki, who joined the eastern forces. It has been said that at first Yukimura followed Ieyasu but, after Ieyasu tried to seize his territory he betrayed Ieyasu. The true motive of Masayuki and Yukimura's decision is disputed with many theories, but there are two main schools of thought: in one, Masayuki made the decision (and Yukimura agreed); he expressed the willingness to take a gamble, so that if he were to join the weak side and win the battle, the Sanada would gain much more power. The other theory is the opposite where they planned a safety net; Masayuki, Yukimura, and Nobuyuki discussed the situation when Ieyasu asked them to state their allegiance clearly, and they decided to join separate sides, so that, regardless of the outcome of the battle, the Sanada clan would survive.