And the children of Israel did evil again in the sight of the LORD: and the LORD strengthened Eglon the king of Moab against Israel, because they had done evil in the sight of the LORD. The children of Israel did evil - They forgat the Lord and became idolaters, and God made those very people, whom they had imitated in their idolatrous worship, the means of their chastisement.
The Lord strengthened Eglon the king of Moab - The success he had against the Israelites was by the especial appointment and energy of God.
He not only abandoned the Israelites, but strengthened the Moabites against them. Eglon is supposed to have been the immediate successor of Balak. Some great men have borne names which, when reduced to their grammatical meaning, appear very ridiculous: the word עגלון Eglon signifies a little calf!