From Adam Clarke's commentary, "Jdg 1:19 -
And the Lord was with Judah, and he drave out the inhabitants of the mountain; but could not drive out the inhabitants of the valley, because they had chariots of iron - Strange! were the iron chariots too strong for Omnipotence? The whole of this verse is improperly rendered. The first clause, The Lord was with Judah should terminate the 18th verse, and this gives the reason for the success of this tribe: The Lord was with Judah, and therefore he slew the Canaanites that inhabited Zephath, etc., etc. Here then is a complete period: the remaining part of the verse either refers to a different time, or to the rebellion of Judah against the Lord, which caused him to withdraw his support. Therefore the Lord was with Judah, and these were the effects of his protection; but afterwards, when the children of Israel did evil in the sight of the Lord, and served Baalim, etc., God was no longer with them, and their enemies were left to be pricks in their eyes, and thorns in their side, as God himself had said. This is the turn given to the verse by Jonathan ben Uzziel, the Chaldee paraphrast: "And the Word of Jehovah was in the support of the house of Judah, and they extirpated the inhabitants of the mountains; but afterwards, When They Sinned, they were not able to extirpate the inhabitants of the plain country, because they had chariots of iron." They were now left to their own strength, and their adversaries prevailed against them. From a work called the Dhunoor Veda, it appears that the ancient Hindoos had war chariots similar to those of the Canaanites. They are described as having many wheels, and to have contained a number of rooms. - Ward's Customs."
From John Wesley's commentary, "Jdg 1:19 - Could not drive - Because of their unbelief, whereby they distrusted God's power to destroy those who had chariots of iron, and so gave way to their own fear and sloth, whereby God was provoked to withdraw his helping hand."
