When the Philistines heard the noise of the shout, they said, What means the noise of this great shout in the camp of the Hebrews? They understood that the ark of Yahweh was come into the camp.
Perhaps the elders of Israel remembered that in Joshua’s conquest of Jericho, the ark played a very important and visible part in the victory (Joshua 6:2-20). Nevertheless, back then the people trusted in Yahweh, not in the ark as a talisman (good luck charm). The custom of taking idols into battle so their gods would deliver them was common among ancient warriors (cf. 2 Samuel 5:21; 1 Chronicles 14:12). Obviously the Israelites were wrong in thinking that the presence of the ark would guarantee success.