The hill country of Ephraim was to the northwest of Michmash.1 As the Philistine army in this area began to retreat and as they saw the army of Saul coming out to follow them, the other Israelites came out of their hiding places (likely in the woods) and joined the fighting.
22 Tous les hommes d'Israël qui s'étaient cachés dans la montagne d'Ephraïm, apprenant que les Philistins fuyaient, se mirent aussi à les poursuivre dans la bataille.