Born in Owari Province (Aichi) as the son of Niwa Nagamasa. The Niwa had originally served the Shiba, the military governors of Owari. In Owari the Oda family was torn by internal strife, and the young Nagahide would soon choose to serve Oda Nobunaga.
From around this time he served Oda Nobunaga and fought in the wars to unite Owari. Later he married a daughter of Nobunaga's elder brother Nobuhiro, adopted by Nobunaga, and came to stand close to Nobunaga's family. Nobunaga trusted Nagahide deeply, and he is said to have written a letter calling him "a friend and a brother."
When Nobunaga marched on Kyoto backing Ashikaga Yoshiaki, Nagahide distinguished himself in the attack that took Mitsukuri Castle of the Rokkaku in Ōmi. Through this march on the capital, a great step in Nobunaga's rise, Nagahide became known as one of the leading retainers at the front of the fighting.
When Sawayama Castle in Ōmi, held by an Azai retainer, surrendered, Nagahide was put in charge of it. Sawayama was a key point on the road linking Kyoto and Gifu and the front line in the war against the Azai and Asakura. Nagahide met Nobunaga's expectations not only in war but also in governing the castle and its lands.
After the fall of the Asakura, Nagahide was given the whole province of Wakasa (southern Fukui), becoming one of the first Oda retainers entrusted with an entire province. Among the retainers he was likened to rice, something one cannot do without, in the saying "Tōkichi is cotton, Gorōza is rice."
When Nobunaga built Azuchi Castle in Ōmi, Nagahide was made general overseer of the work. Over several years he pushed ahead with this new castle of high stone walls and a great keep, which was completed in 1579. Azuchi Castle, as the castle of the ruler of the realm, became the model for later castle building.
When Nobunaga held a grand cavalry parade in Kyoto before the emperor, Nagahide was given the honor of entering first. The event is seen as showing that Nagahide was especially valued even among the senior Oda retainers.
He was in Osaka with Nobunaga's third son Nobutaka, preparing to cross to Shikoku, when the Honnō-ji Incident occurred. Many of his soldiers fled and he could not move at once, but he joined Hashiba Hideyoshi, who had hurried back from the Chūgoku region, and took part in defeating Akechi Mitsuhide at the Battle of Yamazaki.
He attended the Kiyosu Conference, held to decide the heir and the lands of the Oda after Nobunaga's death, together with Shibata Katsuie, Hashiba Hideyoshi and Ikeda Tsuneoki. Nagahide supported Hideyoshi's view, and Nobunaga's grandson Sanbōshi (later Hidenobu) was chosen as heir. This choice helped Hideyoshi's rise.
In the Battle of Shizugatake between Hideyoshi and Shibata Katsuie, Nagahide sided with Hideyoshi and helped him win. After the battle he received Echizen, formerly Katsuie's, and part of Kaga, and entered Kitanoshō Castle. His lands are said to have reached about 1.2 million koku (accounts differ), and he became a senior figure of the Toyotomi regime.
He died of illness at Kitanoshō Castle. It is said he suffered from a serious stomach ailment, and accounts of his last moments differ. After his death his son Nagashige had his lands greatly reduced, but in the Edo period he rebuilt the house as a daimyō. Nagahide was a deeply trusted warrior who supported both Nobunaga and Hideyoshi.
Shibata KatsuieAkechi MitsuhideTakigawa KazumasuOda NobunagaAshikaga YoshiakiToyotomi Hideyoshi
Ōmura SumitadaOda NobunagaHosokawa Yūsai (Fujitaka)Shimazu YoshihiroAshikaga YoshiteruToyotomi HideyoshiAshikaga YoshiakiMaeda Toshiie
People of the Sengoku/Azuchi-Momoyama period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.