(KJV) Isaiah 7:3-7
3 Then said the LORD unto Isaiah, Go forth now to meet Ahaz, thou, and Shearjashub thy son, at the end of the conduit of the upper pool in the highway of the fuller's field; 4 And say unto him, Take heed, and be quiet; fear not, neither be fainthearted for the two tails of these smoking firebrands, for the fierce anger of Rezin with Syria, and of the son of Remaliah. 5 Because Syria, Ephraim, and the son of Remaliah, have taken evil counsel against thee, saying, 6 Let us go up against Judah, and vex it, and let us make a breach therein for us, and set a king in the midst of it, even the son of Tabeal: 7 Thus saith the Lord GOD, It shall not stand, neither shall it come to pass.
But we read different accounts in 2 Chronicles 28 & 2 Kings 16
(KJV) 2 Chronicles 28:5-8
5 Wherefore the LORD his God delivered him into the hand of the king of Syria; and they smote him, and carried away a great multitude of them captives, and brought them to Damascus. And he was also delivered into the hand of the king of Israel, who smote him with a great slaughter.
6 For Pekah the son of Remaliah slew in Judah an hundred and twenty thousand in one day, which were all valiant men; because they had forsaken the LORD God of their fathers. 7 And Zichri, a mighty man of Ephraim, slew Maaseiah the king's son, and Azrikam the governor of the house, and Elkanah that was next to the king. 8 And the children of Israel carried away captive of their brethren two hundred thousand, women, sons, and daughters, and took also away much spoil from them, and brought the spoil to Samaria.
(KJV) 2 Kings 16:5-6
5 Then Rezin king of Syria and Pekah son of Remaliah king of Israel came up to Jerusalem to war: and they besieged Ahaz, but could not overcome him. 6 At that time Rezin king of Syria recovered Elath to Syria, and drave the Jews from Elath: and the Syrians came to Elath, and dwelt there unto this day.
Isaiah only mentions the king of Assyria as the instrument of the Lord to inflict punishment on Judah.
The prophet goes to the extent of giving a sign of assurance (Isaiah 7:13-14).
Ephraim & Syria attack Judah.
Yet the attack still comes, one hundred & twenty thousand slaughtered & two hundred thousand women taken captive.
Was this attack so insignificant so as not to have merited any mention by the prophet?