In that day the Egyptians will become weaklings.

Isaiah 19:1-25
In that day the Egyptians will become weaklings. They will shudder with fear at the uplifted and that the Lord Almighty raises against them.
In that day five cities in Egypt will speak the language of Canaan and swear allegiance to he Lord Almighty. One of them will be called the City of the Sun.
In that day there will be an altar to the Lord in the heart of Egypt,and a monument to the Lord at its border.
It will be a sign and witness to the Lord Almighty in the land of Egypt.
In that day Israel will be the third, along with Egypt and Assyria, a blessing on the  earth. The LordAlmighty will bless them, saying, “Blessed be Egypt my people, Assyria my handiwork, and Israel my inheritance.
This prophecy foretells the disintegration of Egypt: internal strife, followed by conquest, a ruined economy and breakdown of leadership.
Egypt was defeated by Assyria when Sennacherib's army besieged Jerusalem. Further defeats culminated in the sack of Thebes in 663BC, when the Assyrians pillaged centuries of temple treasure.
But God uses the sword for surgery, not anarchy. Verses 16-24 reveal his ultimate purpose: the revelation of himself to the Egyptian people. Amazingly, Egypt and Assyria will be united with Israel in the worship of God, bringing blessing to the whole world. 'That day' is the day of God's final intervention in judgment and salvation on a worldwide scale. The New Testament sees 'that day' as the day of Christ's return.
After Jerusalem feel in 587 there were numerous influential colonies of Jews in Egypt and in Assyria. A copy of the Jewish Temple was even constructed at Leontopolis in Egypt about 170BC. But all that was only a pale shadow of what is envisaged in Isaiah.
Why?
In that day is the day of Jesus Christ return from the heaven. Final intervention in judgment and salvation on a worldwide scale. 
The Lord Almighty will bless them, to those who follow the Jesus Christ.
No matter how strong a nation and country, before the Lord have to be humble and be lower.
How?
God is the Lord, praise to his holy name. In that day all Christian are waiting its coming.