Isaiah 59 begins with an indictment of Israel, listing the offenses it has perpetrated against God. Isaiah 59:16 is a stunner. God saw the unrighteousness of Israel and brought salvation by "His own arm" and by "His righteousness". Note that these proclamations bear the inference that Israel is neither righteous nor able to save itself. These are actually thinly veiled hints that God Himself will come down to redeem His people.
In this, we see another shift occurring. The King who appears in the first third of the book becomes a servant and will, by the hand of God, become a conqueror!
Isaiah 60 expands upon this idea. The glory of the Lord will rise up in Israel. The nations of the world will honor her and her King. The Jews, who were once despised and rejected will be honored for their relationship to their redeeming God.
We hear the words of the conquering Redeemer in Isaiah 61-63. God's people will be lifted up and those who oppress them will be judged.
None of this is reasonable in a worldly sense. Kings don't serve and servants don't conquer. Yet this is God's plan for redeeming His people. It's also the echo of a beautiful truth that will become crystal clear the moment Jesus kneels down and washes the feet of His disciples. The way to eternal victory is through humility and service.