[2] He was famous for his red armour and skill in battle, and was a personal friend of Takeda Shingen.

He was present at the Battle of Mimasetoge in 1569 and captured Yoshida Castle, a Tokugawa possession, during the Mikatagahara Campaign (1572–73).

[3][4] His last campaign was in the ill-fated Battle of Nagashino in 1575, in which he tried to persuade Katsuyori to honorably withdraw.

[5] Ii Naomasa of the Tokugawa clan gained the surviving retainers of the Takeda clan and more widely implemented the ideas of "Masakage's red-colored army," having several units of elite samurai in blood-red armor, to inflict fear and demoralization on enemy troops.

[7] Yamagata is one of the main characters in Akira Kurosawa's epic film Kagemusha.