Metaphor and Simile, or Semaphore or Something Else.

 "The Destruction of Sennacherib"

The Assyrian came down like the wolf on the fold,
And his cohorts were gleaming in purple and gold;
And the sheen of their spears was like stars on the sea,
When the blue wave rolls nightly on deep Galilee.

Like the leaves of the forest when Summer is green,
That host with their banners at sunset were seen:
Like the leaves of the forest when Autumn hath blown,
That host on the morrow lay withered and strown.

For the Angel of Death spread his wings on the blast,
And breathed in the face of the foe as he passed;
And the eyes of the sleepers waxed deadly and chill,
And their hearts but once heaved, and for ever grew still!

And there lay the steed with his nostril all wide,
But through it there rolled not the breath of his pride;
And the foam of his gasping lay white on the turf,
And cold as the spray of the rock-beating surf.

And there lay the rider distorted and pale,
With the dew on his brow, and the rust on his mail:
And the tents were all silent, the banners alone,
The lances unlifted, the trumpet unblown.

And the widows of Ashur are loud in their wail,
And the idols are broke in the temple of Baal;
And the might of the Gentile, unsmote by the sword,
Hath melted like snow in the glance of the Lord! 

Lord Byron. (first pub.1815)

It occurs to me that,  if you're not versed in the old testament,you might be unfamiliar with Sennacherib. He was an assyrian king who rebuilt Nineveh in Mesopotamia, as his capital city. The Judaeans were a thorn in his side, so he took an army to show them who was the boss.

The Sennacherib Prism

In my third campaign I marched against Hatti. Luli, king of Sidon, whom the terror-inspiring glamor of my lordship had overwhelmed, fled far overseas and perished.... As to Hezekiah, the Jew, he did not submit to my yoke, I laid siege to his strong cities, walled forts, and countless small villages, and conquered them by means of well-stamped earth-ramps and battering-rams brought near the walls with an attack by foot soldiers, using mines, breeches as well as trenches. I drove out 200,150 people, young and old, male and female, horses, mules, donkeys, camels, big and small cattle beyond counting, and considered them slaves. Himself I made a prisoner in Jerusalem, his royal residence, like a bird in a cage. I surrounded him with earthwork in order to molest those who were his city's gate. Thus I reduced his country, but I still increased the tribute and the presents to me as overlord which I imposed upon him beyond the former tribute, to be delivered annually. Hezekiah himself, did send me, later, to Nineveh, my lordly city, together with 30 talents of gold, 800 talents of silver, precious stones, antimony, large cuts of red stone, couches inlaid with ivory, nimedu-chairs inlaid with ivory, elephant-hides, ebony-wood, boxwood and all kinds of valuable treasures, his own daughters and concubines. . 

According to the bible, the god of the Hebrews was busy somewhere else, sitting upon cherubim,  when all this happened, but eventually Hezekiah, the king, managed to get a prayer through, by way of the prophet Isaiah, pretty much at the last possible moment, what with Jerusalem being besieged, and Sennacherib about to smash down the walls. 
Well. lo, the wrath of the Lord was pretty mighty, once he'd decided to listen to Hezekiah, who'd been somewhat out of favour, and he sent down an angel that night to do a bit of smiting. Yea verily, for the Lord, despite all his talk of mercy and love, and so on, never could resist a good smiting, and by the morning, so the hebrew record tells, " And it came to pass that night, that the angel of the LORD went forth, and smote in the camp of the Assyrians a hundred fourscore and five thousand; and when men arose early in the morning, behold, they were all dead corpses." (that's a hundred and eighty five thousand, by the way).
So Sennacherib packed up and went home. Interesting that, how histories are written.
Because, there's no mention of those vast losses at all in the Assyrian record.
Herodotus, however, tells us this camp was at Pelusium, far south of Jerusalem:
-Josephus, Antiquities 10;1
Now concerning this Sennacherib, Herodotus also says, in the second
book of his histories, how "this king came against the Egyptian king, who
was the priest of Vulcan; and that as he was besieging Pelusium, he broke
up the siege on the following occasion: This Egyptian priest prayed to God,
and God heard his prayer, and sent a judgment upon the Arabian king." But
in this Herodotus was mistaken, when he called this king not king of the
Assyrians, but of the Arabians; for he saith that "a multitude of mice
gnawed to pieces in one night both the bows and the rest of the armor of
the Assyrians, and that it was on that account that the king, when he had
no bows left, drew off his army from Pelusium." 

 

Other commentators point out that a plague of rodents carries with it disease, and typhus might be what disabled the assyrian army.

 

 

  Ogden Nash- Very Like a Whale*
 

  
One thing that literature would be greatly the better for
Would be a more restricted employment by the authors of simile and
   metaphor.

Authors of all races, be they Greeks, Romans, Teutons or Celts,
Can't seem just to say that anything is the thing it is but have to
   go out of their way to say that it is like something else.

What does it mean when we are told
That that Assyrian came down like a wolf on the fold?
In the first place, George Gordon Byron had enough experience
To know that it probably wasn't just one Assyrian, it was a lot of
   Assyrians.

However, as too many arguments are apt to induce apoplexy and
   thus hinder longevity.
We'll let it pass as one Assyrian for the sake of brevity.
Now then, this particular Assyrian, the one whose cohorts were
   gleaming in purple and gold,
Just what does the poet mean when he says he came down like a
   wold on the fold?

In heaven and earth more than is dreamed of in our philosophy
   there are great many things.
But I don't imagine that among them there is a wolf with purple
   and gold cohorts or purple and gold anythings.
No, no, Lord Byron, before I'll believe that this Assyrian was
   actually like a wolf I must have some kind of proof;
Did he run on all fours and did he have a hairy tail and a big red
   mouth and big white teeth and did he say Woof Woof?

Frankly I think it is very unlikely, and all you were entitled to say,
   at the very most,
Was that the Assyrian cohorts came down like a lot of Assyrian
   cohorts about to destroy the Hebrew host.

But that wasn't fancy enough for Lord Byron, oh dear me no, he
   had to invent a lot of figures of speech and then interpolate them,
With the result that whenever you mention Old Testament soldiers
   to people they say Oh yes, they're the ones that a lot of
   wolves dressed up in gold and purple ate them.

That's the kind of thing that's being done all the time by poets,
   from Homer to Tennyson;
They're always comparing ladies to lilies and veal to venison,
And they always say things like that the snow is a white blanket
   after a winter storm.

Oh it is, is it, all right then, you sleep under a six-inch blanket of
   snow and I'll sleep under a half-inch blanket of unpoetical
   blanket material and we'll see which one keeps warm,
And after that maybe you'll begin to comprehend dimly
What I mean by too much metaphor and simile.

*
"Very Like a Whale" is a quote from a line spoken by Polonius in Shakespeare's play, 'Hamlet',

Ham. Do you see yonder cloud that ’s almost in shape of a camel? Pol. By the mass, and ’t is like a camel, indeed. Ham. Methinks it is like a weasel. Pol. It is backed like a weasel. Ham. Or like a whale? Pol. Very like a whale.

At this point, Hamlet is playing with Polonius, seeking to show that he's an unreliable sycophant, ready to say whatever he thinks is required to keep his mastter happy