It Only Took One Angel
Second Kings, chapter 19, beginning at verse 15, "Then Hezekiah prayed before the Lord, and said: 'O Lord God of Israel, the One who dwells between the cherubim, You are God, You alone, of all the kingdoms of the earth. You have made heaven and earth. Incline Your ear, O Lord, and hear; open Your eyes, O Lord, and see; and hear the words of Sennacherib, which he has sent to reproach the living God.'"
A king of old, Hezekiah was up against an army that he had no power to naturally resist. Being a servant of God, he knew that powers of darkness were challenging the integrity and the keeping power of God himself. And so he prayed! He prayed for a deliverance so powerful that people everywhere would again know that there's only one God, who holds all power in His hand. The Lord answered by sending one angel who struck down an entire army.
You should read the story, and when you have, you might just decide, it's time to pray.