What does Judges 8:19 mean?

Midianite kings known as Zebah and Zalmunna have been captured (Judges 8:10–12). Gideon is harshly questioning them about men they killed at Mount Tabor (Judges 8:18). The pair have responded to the impossible question with flattery. Whether they truly remember what happened or not, they claim the dead mean looked like Gideon: like the sons of a king.

Although the incident is not described, this exchange reveals several things. First, the Midianites did more than just take food from the Israelites (Judges 6:1–5). They murdered people. More shockingly, it reveals that Gideon's own brothers were killed by these two men. Or, at least, by men under their control. Zebah and Zalmunna described the men they killed as being like the sons of a king—which might well have been a dishonest attempt at flattery. Gideon replies by identifying them as the sons of his mother.

With this revelation, the entire story of Gideon comes into sharper focus. Was it the murder of his brothers by the kings of Midian that made him so fearful and timid when the Lord called him to lead the fight (Judges 6:11–15)? Did the Lord choose Gideon, in part, to avenge the murder of his own family members as well as all the others killed in Israel?

And yet, this discovery opens other questions. Among these is Gideon's true motive for chasing down the Midianites even after they fled past the Jordan River. Was he intent on fulfilling God's mission or avenging himself and his family? Perhaps both played a role.

Gideon says to the pair that if they had not killed his brothers, he would not kill them now. He swears this is true "as Yahweh lives." This is a statement of faith in Yahweh, but also a declaration that Gideon's motive for killing these kings is at least partly his own personal revenge.