Judges 1:19

19. And he drave out the inhabitants of the mountain Hebrews, he seized or possessed the mountain. In ordinary cases of foreign invasion the mountains are the fortresses which are last to surrender. But the Israelites, having confidence only in mountain warfare, concentrated their energies upon these fastnesses and secured their possession.

But could not drive out Literally, for not to drive out the inhabitants of the valley; that is, they were not to be driven out, or, as one might say, there was no driving them out. The word rendered valley is עמק , emek, and does not necessarily refer at all to the Philistine plain, which is called the Shephelah, Judges 1:9. Emek denotes any valley, basin, or depression between mountains, and may here refer to plains situated among the mountains of Judah or elsewhere.

Because they had chariots of iron This we are doubtless to take as the occasion, not the necessitating cause, of Judah’s ultimate failure to conquer all his foes. Iron chariots could not withstand the forces of Joshua (Joshua 11:4-9) nor of Barak, (Judges 4:15,) when the people of Jehovah fought with faith in his power, and Judah might likewise have conquered; but we understand that, after many triumphs, when Judah was brought to face these chariots of iron instruments of warfare strange and terrible he hesitated, wavered, gave way to fear, and thus lost faith in God, and then there was no driving out his enemy.