Board Thread:Theories and Speculation/@comment-1018594-20150111145319/@comment-5832352-20150112054306

You're assuming that he died in battle. You forget that there are things he was willing to fight and die for. When he was trying to bring peace with the Uchiha, Madara said he would only accept peace for the life of his brother if Hashirama either killed himself or Tobirama. Hashi easily chose himself.

Maybe in 1 of the many border wars, a group of young genin were captured, or his own kid(s). In a simple demand: we will offer peace (end of the war) and the young shinobi in exchange for the Kage's life. Everyone reviewed and said that there was no other way to save the young shinobi. And without hesitating, Hashi sacrificed himself.