When did Neji's father die?

Answer 1

It was the incident with Kumogakure (Hidden Cloud)'s and Konohagakure's peace treaty. The two villages, which were at war with one another, apparently decided to sign a treaty, and for this representatives from Kumogakure arrived. On the same day, the very same curse seal that tortured Hyuuga Hizashi was put upon Neji himself; and that night, the ambassador from the Lightning country attempted to kidnap Hinata, revealing that the intention of the "treaty" was all along to get into the Fire country and acquire the secret of Byakugan. Hiashi detected the intruder and killed him at once, for which Kumogakure, absurdly, requested payback in the form of Hiashi's dead body. That day, Neji's father was sent to his death instead of Hiashi, and Neji grew up believing that his father was sent against his will to protect the Hyuuga clan's secret bloodline.