The fortress; either Samaria, their chief fortress; or all their fortress or strong holds, the singular number being put for the plural; or all their strength and glory, which answers to the kingdom in the next clause. And the remnant of Syria; or, and from (which particle is easily understood from the former clause) the remnant of Syria. So the sense is, The remainders of Damascus and Syria shall be a headless body, a people without a king. They shall be as the glory; an ironical speech, implying their contemptible condition; for their glory is supposed to be departed from them, by what he had already said of them. The sense is, Syria shall have as much glory as Israel, i.e. neither of them shall have any at all.
Related Commentaries of Isaiah 17:3
Isaiah 17:3
3 The fortress also shall cease from Ephraim, and the kingdom from Damascus, and the remnant of Syria: they shall be as the glory of the children of Israel, saith the LORD of hosts.