Parshat Lech L'cha describes how Lot was captured in the battle of four kings against five kings. When Avraham heard, he mounted a night-time attack to rescue him. This got me wondering: was a night-time raid a typical tactic for the time (a) at all or (b) for purposes of conducting a rescue? Or would a battle-field battle (with both sides aware) have been the way fights were usually conducted? I'm wondering whether Avraham followed the local norms or if he didn't and from that we can learn how far we must go in rescuing captives.
I understand that the victory was a miracle, but since we do not rely on miracles I am wondering about Avraham's context in planning the attack. Did he do what was considered normal in that setting, or were his methods and/or haste unusual and we should learn from that? Or, realized since asking the question, would his captors have expected not a fight at all, but a ransom negotiation?