Then the Spirit of Yahweh came on Jephthah, and he passed over Gilead and Manasseh, and passed over Mizpeh of Gilead, and from Mizpeh of Gilead he passed over to the children of Ammon.
As Yates noted, "Jephthah here made a series of journeys,"[16] and the implication is clear enough that Jephthah did so under the direction of the Spirit of God.  We are not told exactly what the purpose of those trips was, but, in all likelihood, it was to enlist as many as possible in the army with which Jephthah would meet the foe.