Are you sure? Died in the war doesn’t necessarily mean killed by a fodder. Let look at 3rd Raikage. He died taking on an army by himself. May have been a similar deal with Hashi. Or maybe he gave his life to save others? Somethings like that.DB1. It was said he died in the War.
So he got killed by someone or a group of someone's like Tobirama. Smfh