isaiah 7:8 For the head of Syria is Damascus, and the head of Damascus is Rezin; and within threescore and five years shall Ephraim be broken, that it be not a people. - Free Bible Online

      8. head--that is, in both Syria and Israel the capital shall remain as it is; they shall not conquer Judah, but each shall possess only his own dominions.
      threescore and five . . . not a people--As these words break the symmetry of the parallelism in this verse, either they ought to be placed after "Remaliah's son," in Isa 7:9, or else they refer to some older prophecy of Isaiah, or of Amos (as the Jewish writers represent), parenthetically; to which, in Isa 7:8, the words, "If ye will not believe . . . not be established," correspond in parallelism. One deportation of Israel happened within one or two years from this time, under Tiglath-pileser (2Ki 15:29). Another in the reign of Hoshea, under Shalmaneser (2Ki 17:1-6), was about twenty years after. But the final one which utterly "broke" up Israel so as to be "not a people," accompanied by a colonization of Samaria with foreigners, was under Esar-haddon, who carried away Manasseh, king of Judah, also, in the twenty-second year of his reign, sixty-five years from the utterance of this prophecy (compare Ezr 4:2, 3, 10, with 2Ki 17:24; 2Ch 33:11) [USHER]. The event, though so far off, was enough to assure the people of Judah that as God, the Head of the theocracy, would ultimately interpose to destroy the enemies of His people, so they might rely on Him now.

JFB.