What does Judges 10:18 mean?

The Ammonites have oppressed Israel for eighteen years (Judges 10:6–9). This enemy who has brought such misery is now staging another offensive. The Ammonites have collected their army in the region of Gilead east of the Jordan River. The Israelites have responded by masing their own troops at a place in Gilead known as Mizpah. The two forces are mounting for an impending battle.

Here, a problem is revealed. The Israelites in Gilead have no military leader. Obviously, there would have been some with more experience than others. And some men were likely natural leaders. But it's clear none of their options are the right one; nobody has risen to provide strategy, direction, and boldness for the fighters of Gilead to follow. So, Gilead's leaders agree together to make a grand offer to whatever qualified man will take over. The person who leads them against the Ammonites will be granted the role of head—the "chief" or "captain"—over all the people in Gilead. Presumably, he will take this role as soon as the Ammonites are defeated.

The following chapter reveals who this man will be and how he will come to be selected. The prior judge, Gideon, was involved in questionable choices and family sins (Judges 8:27–31). Yet, he's remembered mostly for his victories (Judges 8:22–23). Jephthah will also rescue Israel, yet he will be best known for a single unwise and controversial promise (Judges 11:30).