Isaiah 7:1 And it came to pass in the days of Ahaz the son of Jotham, the son of Uzziah, king of Judah, that Rezin the king of Syria, and Pekah the son of Remaliah, king of Israel, went up toward Jerusalem to war against it, but could not prevail against it.
2 And it was told the house of David, saying, Syria is confederate with Ephraim. And his heart was moved, and the heart of his people, as the trees of the wood are moved with the wind.
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.
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.
9 And the head of Ephraim is Samaria, and the head of Samaria is Remaliah's son. If ye will not believe, surely ye shall not be established.

Syria and Israel joined together to lay siege upon Jerusalem, capital of Judah. God told Isaiah to go and meet Ahaz and tell him that Samaria and Syria would fail to gain the victory. Isaiah prophesied that within sixty-five years (three score and five years) Ephraim would be broken and be not a people. This was in the days of Pekah and Rezin, 742 B. C.  As a warning Isaiah says "If you will not believe this, you will not be established." Did Ahaz believe this?

"For the LORD brought Judah low because of Ahaz king of Israel; for he made Judah naked, and transgressed sore against the LORD.  And Tilgathpilneser king of Assyria came unto him, and distressed him, but strengthened him not.  For Ahaz took away a portion out of the house of the LORD, and out of the house of the king, and of the princes, and gave it unto the king of Assyria: but he helped him not.  And in the time of his distress did he trespass yet more against the LORD: this is that king Ahaz.  For he sacrificed unto the gods of Damascus, which smote him: and he said, Because the gods of the kings of Syria help them, therefore will I sacrifice to them, that they may help me. But they were the ruin of him, and of all Israel.  And Ahaz gathered together the vessels of the house of God, and cut in pieces the vessels of the house of God, and shut up the doors of the house of the LORD, and he made him altars in every corner of Jerusalem.  And in every several city of Judah he made high places to burn incense unto other gods, and provoked to anger the LORD God of his fathers." 2 Chronicles 28:19-25

Clearly Ahaz not only did not believe it, he also did not even care obey God! 

So how did Isaiah's 65 year prophecy come to be fulfilled? 

Isaiah 8:1 Moreover the LORD said unto me, Take thee a great roll, and write in it with a man's pen concerning Mahershalalhashbaz.
2 And I took unto me faithful witnesses to record, Uriah the priest, and Zechariah the son of Jeberechiah.
3 And I went unto the prophetess; and she conceived, and bare a son. Then said the LORD to me, Call his name Mahershalalhashbaz.
4 For before the child shall have knowledge to cry, My father, and my mother, the riches of Damascus and the spoil of Samaria shall be taken away before the king of Assyria.
5 The LORD spake also unto me again, saying,
6 Forasmuch as this people refuseth the waters of Shiloah that go softly, and rejoice in Rezin and Remaliah's son;
7 Now therefore, behold, the Lord bringeth up upon them the waters of the river, strong and many, even the king of Assyria, and all his glory: and he shall come up over all his channels, and go over all his banks:
8 And he shall pass through Judah; he shall overflow and go over, he shall reach even to the neck; and the stretching out of his wings shall fill the breadth of thy land, O Immanuel.

As studied earlier in Deuteronomy 28, Israel or Samaria was taken captive and scattered by the Assyrians in 723 B.C., 19 years after Isaiah prophesized the fall of Syria and Samaria.  Ahaz should have believed Isaiah, the prophet of God.  Because he didn't, Judah was taken in 677 B.C., exactly 65 years after Isaiah's prophecy.   So we can see that both starting points of the 2520s were proclaimed by God through His faithful prophet Isaiah. What about Isaiah's two sons, where to they fit in?  Shearjashub was the son that Isaiah was told to take with him when he was to give the king of Judah the message from God.  Shearjashub means: "The remnant shall return."  Mahershalalhashbaz was the son that was born in confirmation of the demise of Syria and Samaria.  Mahershalalhashbaz means: "In making speed to the spoil he hasteneth the prey."

We learned in Deuteronomy 28 that Israel or Samaria were going to be scattered out of existence just like the name Mahershalalhashbaz suggests - making speed to the spoil.  Later we will learn about how at the end of Judah's 2520 there was a remnant gathered just like the name Shearjashub means.