The Jephthah narrative does not begin with the deliverance from the Ammonites. The momentum of the story is interrupted here while we are introduced to Jephthah and told a little of his personal history, from many years before, when Jephthah was driven out of his father’s house by his brothers. This is formally set off from the main thread of the narrative by “now Jephthah.”
1 Now Jephthah the Gileadite was a mighty warrior, but he was the son of a prostitute. Gilead was the father of Jephthah.