2 Kings 19:34-35 (NKJV)
"For I will defend this city, to save it For My own sake and for My servant David's sake."
And it came to pass on a certain night that the angel of the Lord went out, and killed in the camp of the Assyrians one hundred and eighty-five thousand; and when people arose early in the morning, there were the corpses--all dead.
God had heard enough of this obstinate King of Assyria who had been boasting how he was going to conquer Jerusalem. Hezekiah, who was a good king of Judah, had prayed earnestly that God would deliver them from this threat. Isaiah the prophet confirmed that God would indeed deliver them.
Angels are a the popular topic of a number of books and articles these days you can find on the newsstands and in bookstores these days. You see them depicted as these sweet chubby little cherubs or as a soft effeminate young men. Think about what this angel did after dinner one evening, he wiped out 185,000 troops. I just have to believe that you don't mess around with angels!