The battle against the Amalekites lasted one whole day. Most probably it took place on the same day that Saul fought and died in his battle against the Philistines (cf. 1 Samuel 31:1–13).1 David waited until dawn before his attack.2 He likely moved with great stealth at the beginning and was able to do so for some time given the reveling that took place during the night (Cf. 1 Samuel 30:16). No doubt many of the Amalekites were fully satiated and were too drunk to fight properly.3
17 And David struck them down from twilight until the evening of the next day, and not a man of them escaped, except four hundred young men, who mounted camels and fled.