In 1600, Musashi is said to have participated in the Battle of Sekigahara. For a long time, the prevailing opinion has been that Musashi participated in the Sekigahara battle on the Western Army side due to the fact that Shinmen clan was longtime vassal to the Ukita clan. However, recent research by modern Japanese historians such as Masahide Fukuda and Watanabe Daimon about Musashi has opined that Musashi and his father, Shinmen Munisai, actually sided with The Eastern army during the war, based on the historical records that Munisai no longer served the Ukita clan, and the clan records of Kuroda clan, ally of Tokugawa Ieyasu during the war, had recorded the name of Shinmen Munisai among their vassals who participated in the war. Daimon, who quoted the "Matsui clan Document", has opined that the notion that Musashi fought on the losing side of Western Army, both in Sekigahara and in Osaka siege 14 years later, were only based on legendary romanticism about Musashi being a ronin. While the primary history records indicated that Musashi always fought on the side of Tokugawa, who emerged victorious in both conflicts. The main issue debated, was if Musashi fought in the Sekigahara battle with the Eastern Army main forces, under Tokugawa, or did he fight in Ishigakibaru of western province theater under the Eastern Army commander Kuroda Yoshitaka. Daimon more leaned to the opinion that Musashi fought in Ishigakibaru instead of Sekigahara, by historical record of "The Transmission of Military Art to Master Bushu Genshin" Meanwhile, Fukuda has pointed out that the name of Munisai appeared in Kuroda clan record under the category of "Kogofudai", or Kuroda clan vassals who had entered service before 1586. Based on this fact, Fukuda concluded it was natural that Munisai and Musashi were on the Tokugawa side during the war, just as the Kuroda clan which they served.
In 1600, Musashi is said to have participated in the Battle of Sekigahara. For a long time, the prevailing opinion has been that Musashi participated in the Sekigahara battle on the Western Army side due to the fact that Shinmen clan was longtime vassal to the Ukita clan. However, recent research by modern Japanese historians such as Masahide Fukuda and Watanabe Daimon about Musashi has opined that Musashi and his father, Shinmen Munisai, actually sided with The Eastern army during the war, based on the historical records that Munisai no longer served the Ukita clan, and the clan records of Kuroda clan, ally of Tokugawa Ieyasu during the war, had recorded the name of Shinmen Munisai among their vassals who participated in the war. Daimon, who quoted the "Matsui clan Document", has opined that the notion that Musashi fought on the losing side of Western Army, both in Sekigahara and in Osaka siege 14 years later, were only based on legendary romanticism about Musashi being a ronin. While the primary history records indicated that Musashi always fought on the side of Tokugawa, who emerged victorious in both conflicts. The main issue debated, was if Musashi fought in the Sekigahara battle with the Eastern Army main forces, under Tokugawa, or did he fight in Ishigakibaru of western province theater under the Eastern Army commander Kuroda Yoshitaka. Daimon more leaned to the opinion that Musashi fought in Ishigakibaru instead of Sekigahara, by historical record of "The Transmission of Military Art to Master Bushu Genshin" Meanwhile, Fukuda has pointed out that the name of Munisai appeared in Kuroda clan record under the category of "Kogofudai", or Kuroda clan vassals who had entered service before 1586 Based on this fact, Fukuda concluded it was natural that Munisai and Musashi were on the Tokugawa side during the war, just as the Kuroda clan which they served.