What does Judges 11:20 mean?
Through messengers, Jephthah is describing everything Israel did to try to avoid conflict while crossing over the Jordan River during time of Moses. He is delivering this history lesson in response to the Ammonite king's wrong assertion: that Israel stole the land of Gilead from Ammon (Judges 11:12–14). Jephthah's main point has been that the Ammonites were not even occupying the land that close to the Jordan (Judges 11:15–19).Instead, the land was then occupied by the Amorites, an entirely different people. The Israelites wanted to pass through the land to get to the other side of the Jordan, so they sent a message to Sihon, king of the Amorites, asking permission. Sihon never answered the request. He did not trust the Israelites, assuming they were there to take the land from him. Instead of answering their question, he quickly gathered his army at Jahaz, and attacked the Israelites (Numbers 21:21–23).
Jephthah is proving that the king of Ammon was not only wrong about Ammonites occupying the land at the time, but he was also wrong about who attacked whom. It was the local Amorites that attacked Israel, not the other way around.
Judges 11:12–28 is Jephthah's attempt to negotiate with the Ammonites. He exchanges messages with the king of Ammon, asking the reason for this war on their land. Jephthah corrects the king's response that Israel wrongly took the land from them during the time of Moses. He offers several forms of rebuttal. Jephthah notes that Ammon was never in control of Gilead. Instead, the Amorites attacked Israel and God have his people victory. Greater kings have not attempted to take the region away; it had not been disputed for centuries. However, the Ammonite king will not listen.
A man named Jephthah is driven away from his home in Gilead by jealous brothers. He settles in Tob, where he becomes warrior chief of a criminal band. Gilead's elders later recruit Jephthah to lead the fight against their Ammonite oppressors. After a failed negotiation attempt, Jephthah vows to make a burnt offering to the Lord of whatever comes to meet him if God gives him victory over the Ammonites. Israel thoroughly defeats Ammon, and Jephthah's daughter, his only child, greets him. Jephthah carries out his vow after his daughter grieves never marrying or having children.