You are strongly recommended to add to your library the excellent revised edition of Harper's Bible Dictionary titled, The Harper Collins Bible Dictionary, Revised Edition [book review], edited by Paul J. Achtemeier, with the Society of Biblical Literature (NY: Harper Collins, 1996). It is currently the best one-volume Bible dictionary in English, and it is available at Border's Books, Christian Science Reading Rooms, http://www.borders.com, or http://www.christianbook.com.

Jephthah (Heb., ‘he opens’; cf. the place name Iptahel, ‘God opens [the womb?],’ Josh. 19:14, 27), a Gileadite who delivered Israel from Ammonite domination. Jephthah sacrificed his daughter to fulfill a vow, suppressed an Ephraimite force in Gilead, and judged Israel six years (Judg. 10:6-12:7).

Born the son of a harlot, Jephthah was disowned and driven out from his family. In the district of Tob near the modern Jordan-Syria border, he gathered a band of mercenaries and was later recalled by the elders of Gilead. Ammonite forces had invaded Gilead and penetrated across the Jordan into Judah, Benjamin, and Ephraim. The elders of Gilead made Jephthah head and ruler, negotiations culminating in Jephthah’s vows before Yahweh, at Mizpeh (in the vicinity of Jebel Jal‘ad, south of the River Jabbok).

The territory disputed in the negotiations had belonged earlier to the Amorite kingdoms north of the Arnon River, which were defeated by Israel under Moses (Judg. 11:14-28; Num. 21). The territory was subsequently taken by Moab (Judg. 3:12-30). When Ammon became strong enough to press its own claims against Israel, the Ammonite king made claims and charges in the name of Moabite sovereignty over the disputed territory (perhaps claiming to hold it in trust). Jephthah recognized the jurisdiction of Chemosh, god of Moab, for diplomatic purposes, but argued that because God’s gift to Israel was far older, Israel had not seized Ammonite land. When negotiations failed, Jephthah toured Gilead and Manasseh, presumably to muster the army, and returned to Mizpeh. From Mizpeh Israel moved to meet the Ammonites, defeating them along a line from southern Aroer (the northern edge of the Arnon gorge) to Abel-keramim (probably Tell el-Umeiri at the northern end of the Madeba plain). As a result, Ammon was pushed back to the desert fringe.

Upon accepting his commission, Jephthah made a vow that if he were to return victorious, he would sacrifice whatever emerged first from his house (Judg. 11:30-31; Iron Age dwellings, like many Palestinian village houses today, incorporated space for small cattle). The first creature to emerge was his only child, a daughter, who refused to let Jephthah break his vow. She requested two months to wander the hills with her dear friends, lamenting her virginity (childlessness; Judg. 11:39-40). The story serves to explain the otherwise obscure four-day rite observed annually by the daughters of Israel. Human sacrifice, a horror neither condoned nor unknown in ancient Israel, is here secondary to the irrevocability of the vow.

In the final story of the Jephthah cycle, Ephraimites crossed into Gilead, complaining that Jephthah had not summoned them to the Ammonite war and threatening to burn his house (Judg. 12:1). Again negotiations failed and Jephthah was victorious in the fighting. Gileadites used a password, shibboleth, to betray dialect differences, and many Ephraimites were slain at the Jordan fords (Judg. 12:5-6). Joshua 22 describes an earlier confrontation of Israelite tribes in the same area.