Read Isaiah 27.
True prophecy is telling history in advance. After the death of Solomon, the land divided into two kingdoms: Israel in the north and Judah in the south. In Isaiah's day, the Assyrians were cruelly conquering every nation in their path. The LORD told Isaiah to prophesy that Assyria would crush Israel. As a result, Judah would experience great pressure but God would protect them a while longer. Later, the Babylonians conquered Assyria and then captured Judah to take them away in exile (v.8).
Not since the time of Solomon had there been a single nation of Jews on that land under its own rule until 1948; roughly, 3000 years. Still, the world has yet to see what God told Isaiah would ultimately happen.
Four times the phase "in that day" or "in the days to come" appear. Most often, that is a trigger phrase concerning the time of Christ's return and events that will follow. Here is some history in advance.
1. The LORD will slay his enemies. (v.1)
This is the exact picture of Jesus in Revelation 19:11-16. The sword of the LORD is the Word of God. As we are told in Genesis 1, He spoke creation into existence. So, in His return He will speak the command and all the enemies of God will be defeated.
2. The LORD will restore Israel spiritually. (vv.2-6)
The spiritual picture of God's relationship with the Jews is one of taking care of His vineyard. Previously, the message to Isaiah was that the vineyard produced only wild grapes, so God would remove His protection of His people. But these verses look forward to a day when the Jews will "blossom" "and fill the whole world with fruit."
3. The LORD will forgive the sin of Israel. (vv.7-11)
God had to deal with their sin of unbelief and blatant false worship. The exile of Judah that took place in 586 B.C. was predicted. To this day, the world has not seen the fulfillment of this national removal of sin and restoration. There is only one solution to sin and that is the forgiveness God alone offers through the shed blood of Jesus, the Messiah. By faith the godly of the Old Testament looked forward to the cross, as we look back to it in faith for our complete and final atonement. One day, the Jews will embrace Jesus as the Messiah and know this forgiveness personally and nationally. The Apostle Paul wrote clearly concerning this in Romans 9-11 and even quotes Isaiah several times to prove his case. He then concluded, "And in this way all Israel will be saved, as it is written..." (Romans 11:26)
4. The LORD will be worshiped in Jerusalem. (vv.12-13)
The entire region that is in such turmoil and terror today will "in that day" be sacred territory. Jesus will reign for 1,000 years from Jerusalem and the world will come to bow before Him.
The good news is that anyone may experience God's personal forgiveness and life-restoration right now by calling on Jesus.