Who was Jephthah?
Jephthah was a ninth judge of the Israelites. His antecedents are obscure. Assuming Gilead to be the actual name of his father, his mother was a harlot. He was driven from home on account of his illegitimacy, and went to the land of Tobit in Eastern Syria (Jdg 11:2,3). Here he and his followers lived the life of freebooters.
The Israelites beyond the Jordan being in danger of an invasion by the Ammonites, Jephthah was invited by the elders of Gilead to be their leader (Jdg 11:5,6). Remembering how they had expelled him from their territory and his heritage, Jephthah demanded of them that in the event of success in the struggle with the Ammonites, he was to be continued as leader.
This condition being accepted he returned to Gilead (Jdg 11:7-11). The account of the diplomacy used by Jephthah to prevent the Ammonites from invading Gilead is possibly an interpolation, and is thought by many interpreters to be a compilation from Nu 20 through 21. It is of great interest, however, not only because of the fairness of the argument used (Jdg 11:12-28), but also by virtue of the fact that it contains a history of the journey of the Israelites from Lower Egypt to the banks of the Jordan.
This history is distinguished from that of the Pentateuch chiefly by the things omitted. If diplomacy was tried, it failed to dissuade the Ammonites from seeking to invade Israel. Jephthah prepared for battle, but before taking the field paused at Mizpeh of Gilead, and registered a vow that if he were successful in battle, he would offer as a burnt offering to Yahweh whatsoever should first come from his doors to greet him upon his return (Jdg 11:29-31).
The battle is fought, Jephthah is the victor, and now his vow returns to him with anguish and sorrow. Returning to his home, the first to greet him is his daughter and only child. The father's sorrow and the courage of the daughter are the only bright lights on this sordid, cruel conception of God and of the nature of sacrifice.
That the sacrifice was made seems certain from the narrative, although some critics choose to substitute for the actual death of the maiden the setting the girl apart for a life of perpetual virginity. The Israelite laws concerning sacrifices and the language used in Jdg 11:39 are the chief arguments for the latter interpretation. The entire narrative, however, will hardly bear this construction (11:34-40).
Jephthah was judge in Israel for 6 years, but appears only once more in the Scripture narrative. The men of Ephraim, offended because they had had no share in the victory over the Ammonites, made war upon Gilead, but were put to rout by the forces under Jephthah (Jdg 12:1-6).
IBSE, "Isaac" (in the public domain) with minor edits.