was a Japanese daimyo

Daimyo

is a generic term referring to the powerful territorial lords in pre-modern Japan who ruled most of the country from their vast, hereditary land holdings...

 of the Sengoku period

Sengoku period

The or Warring States period in Japanese history was a time of social upheaval, political intrigue, and nearly constant military conflict that lasted roughly from the middle of the 15th century to the beginning of the 17th century. The name "Sengoku" was adopted by Japanese historians in reference...

. He was the second generation lord of the Saitō clan

Saito clan

The was a Japanese clan in Mino Province during the Sengoku period in the 16th century. According to records, the Saitō clan descended from the Fujiwara clan...

.

Early life

Yoshiatsu was born in Mino Province

Mino Province

, one of the old provinces of Japan, encompassed part of modern-day Gifu Prefecture. It was sometimes called . Mino Province bordered Echizen, Hida, Ise, Mikawa, Ōmi, Owari, and Shinano Provinces....

 in 1527, the eldest son of Saitō Dōsan

Saito Dosan

was a daimyo who dramatically rose and also fell from power in Sengoku period Japan. He was also known as the for his ruthless tactics.-Life:Originally a wealthy merchant from Yamashiro Province , he entered the service of Nagai Nagahiro of Mino Province , assuming the name Nishimura Kankurô.He...

. Some theorize that Yoshitatsu was in fact the son of Toki Yorinari

Toki Yorinari

was a son of Toki Masafusa and final ruling head of the Toki clan during the latter years of the Sengoku period of feudal Japan. As daimyo of Mino Province, he had hired Saito Dosan as his retainer in the 1520s, but was overthrown and expelled from the province by Dosan in a coup d'état in 1542...

, the former ruler of Mino. Whether true or not, this helped bring former retainers of the Toki clan into the Saitō clan's service.

Yoshitatsu declared rebellion against his father in an attempt to obtain control. Decisively defeating his father at the Battle of Nagaragawa

Battle of Nagaragawa

The was a battle that took place along the banks of the Nagara River in Mino Province in April 1556. It was a battle between Saitō Dōsan and his son, Saitō Yoshitatsu.-Background:...

 in 1556, Yoshitatsu wiped out any opposition within the clan and declared himself as Second Head of Saitō.

Aftermath

Yoshitatsu's victory over his father encouraged many other warlords, such as Oda Nobunaga

Oda Nobunaga

was the initiator of the unification of Japan under the shogunate in the late 16th century, which ruled Japan until the Meiji Restoration in 1868. He was also a major daimyo during the Sengoku period of Japanese history. His opus was continued, completed and finalized by his successors Toyotomi...

, to fight after his forts were intentionally destroyed and passage into Mino was restricted. Yoshitatsu died of illness in 1561. The young Saitō Tatsuoki

Saito Tatsuoki

was a daimyo in Mino Province during the Sengoku period and the third generation lord of the Saitō clan. He was a son of Saitō Yoshitatsu, and a grandson of Saitō Dōsan. He was also a nephew of Oda Nobunaga's first wife, Nōhime, herself a daughter of Saitō Dōsan....

 succeeded as the Saitō clan's third head.

See also

• Oda Nobunaga
  Oda Nobunaga
  was the initiator of the unification of Japan under the shogunate in the late 16th century, which ruled Japan until the Meiji Restoration in 1868. He was also a major daimyo during the Sengoku period of Japanese history. His opus was continued, completed and finalized by his successors Toyotomi...
  
  
• Saitō Dōsan
  Saito Dosan
  was a daimyo who dramatically rose and also fell from power in Sengoku period Japan. He was also known as the for his ruthless tactics.-Life:Originally a wealthy merchant from Yamashiro Province , he entered the service of Nagai Nagahiro of Mino Province , assuming the name Nishimura Kankurô.He...
  
  
• Saitō Tatsuoki
  Saito Tatsuoki
  was a daimyo in Mino Province during the Sengoku period and the third generation lord of the Saitō clan. He was a son of Saitō Yoshitatsu, and a grandson of Saitō Dōsan. He was also a nephew of Oda Nobunaga's first wife, Nōhime, herself a daughter of Saitō Dōsan....