Albert Barnes Commentary Judges 3:9

"And when the children of Israel cried unto Jehovah, Jehovah raised up a saviour to the children of Israel, who saved them, even Othniel the son of Kenaz, Caleb`s younger brother." — Judges 3:9 (ASV)

Othniel was already distinguished in Joshua’s lifetime as a brave and successful leader. See Joshua 15:16-17.