"Then Hezekiah worked hard at repairing all the broken sections of the wall, erecting towers, and constructing a second wall outside the first. He also reinforced the supporting terraces in the City of David and manufactured large numbers of weapons and shields. He appointed military officers over the people ad assembled them before him in the square at the city gate. Then Hezekiah encouraged them by saying: "Be strong and courageous! Don't be afraid or discouraged because of the king of Assyria or his mighty army,for there is a power far greater on our side! He may have a great army, but they are merely men.We have the Lord our God to help us and to fight our battles for us!Hezekiah's words greatly encouraged the people.
This is what my Bible Commentary says: Hezekiah could see with eyes of faith. The number of his opponents meant nothing as long as he was on the Lord's side. Victory is "not by force nor by strength, but by My Spirit, says the Lord of Heaven's Armies (Zechariah 4: 6).