was a daimyo of the Hatakeyama clan

Hatakeyama clan

The ' was a Japanese samurai clan. Originally a branch of the Taira clan and descended from Taira no Takamochi, they fell victim of political intrigue in 1205, when Hatakeyama Shigeyasu, first, and his father Shigetada later were killed in battle by Hōjō forces in Kamakura...

 and, according to some accounts, invented the horo, a stiffened cloak used by messengers and bodyguards to improve their visibility on the battlefield, and to act as an arrow-catcher.

Masanaga is most well known for his disputes in 1467 with Hatakeyama Yoshinari

Hatakeyama Yoshinari

was a Japanese samurai and feudal lord of the Muromachi period , who is most well known for his rivalry with Hatakeyama Masanaga over the position of Kanrei, or Shogun's Deputy....

 over the position of Kanrei

Kanrei

or, more rarely, kanryō, was a high political post in feudal Japan; it is usually translated as Shogun's Deputy. After 1349, there were actually two Kanrei, the Kyoto Kanrei and the Kantō Kanrei....

. This grew out of the larger conflict between Hosokawa Katsumoto

Hosokawa Katsumoto

was one of the Kanrei, the Deputies to the Shogun, during Japan's Muromachi Period. He is famous for his involvement in the creation of Ryōan-ji, a temple famous for its rock garden, and for his involvement in the Ōnin War, which sparked the 130-year Sengoku period.His conflicts with his...

 and Yamana Sōzen, which escalated into the Ōnin War

Onin War

The ' was a civil war that lasted 10 years during the Muromachi period in Japan. A dispute between Hosokawa Katsumoto and Yamana Sōzen escalated into a nationwide war involving the Ashikaga shogunate and a number of daimyo in many regions of Japan....

. Masanaga and Yoshinari were largely stalemated for much of this period, as Yamana and Hosokawa Katsumoto warned that the first to engage in battle within the capital would be declared a rebel. Becoming a "rebel" meant losing alliances as well as honor. Both were soon sucked into the larger war, however, and Hatakeyama Masanaga ended up fighting Ōuchi Masahiro

Ouchi Masahiro

was a member of the Ōuchi family and general in the Ōnin War, serving Yamana Sōzen. He battled numerous times with Yamana's rival, Hosokawa Katsumoto, at one point commanding 20,000 men and 2,000 boats, moving his troops by land as well as by sea...

, one of Yamana's generals.