Matthew Arnold - Poetry

I don't know that I've heard of Matthew Arnold before nor this poem, 'Dover Beach'.  The book describes him as a 'major English poet and social critic' and coincidentally, he was a contemporary of John Stuart Mill. 

The sea is calm tonight.
The tide is full, the moon lies fair
Upon the straits; - on the French coast the light
Gleams and is gone; the cliffs of England stand,
Glimmering and vast, out in the tranquil bay,
Come to the window, sweet is the night-air!
Only, from the long line of spray
Where the sea meets the moon blanch'd land,
Listen! you hear the grating roar
Of pebbles which the waves draw back, and fling,
At their return, up the high strand,
Begin, and cease, and then again begin,
With tremulous cadence slow, and bring
The eternal note of sadness in.

Sophocles long ago
Heard it on the Aegean, and it brought
Into his mind the turbid ebb and flow
Of human misery; we
Find also in the sound a thought,
Hearing it by this distant northern sea.

The Sea of Faith
Was once, too, at the full, and round earth's shore
Lay like the folds of a bright girdle furl'd.
But now I only hear
Its melancholy, long, withdrawing roar,
Retreating, to the breath
Of the night-wind, down the vast edges drear
And naked shingles of the world.

Ah, love, let us be true
To one another! for the world, which seems
To lie befure us like a land of dreams,
So various, so beautiful, so new,
Hath really neither joy, nor love, nor light,
And we are here as on a darkling plain
Swept with confused alarms of struggle and flight,
Where ignorant armies clash by night.

So we start with a sound.  The sound of the ocean roaring and tumbling and for the author, that brings to mind Sophocles.  For Sophocles it meant the 'turbid ebb and flow/of human misery'.  For Arnold, it also brings to mind the 'Sea of Faith' which he says once surrounded the earth but is now 'retreating'.  He cautions that this new world, without the Sea of Faith, looks beautiful but 'hath really neither joy, nor love, nor light'.
My guess is that I'd need to dig deeply into Arnold's beliefs before I really understood what he is trying to say.  I don't know if he means that the industrial world is ruining the beauty of the more agrarian one.  Or if the rise of reason is ruining the connection with religion.  Or maybe utilitarian thought is debasing better romantic thought and the inherent worth of each person.  I just honestly don't know. 
The end is striking.  I think the key phrase is 'as on a darkling plain'.  I'm sure I've heard that before.  The idea of ignorant armies, struggling and clashing in the night is a great metaphor too.  I've felt that exact way when hearing political arguments that seem to miss the point. 
Do I like this poem?  I'm not sure.  The language doesn't sing for me and there is nothing especially clever in it's form.  The sentiment is ambiguous at best, thought I doubt that was true when it was written.  Not my favorite, I guess, but that's with a huge caveat as to what it might be.  So, please pardon me, I'll just be here on my own darkling plain, confused and ignorant.