If any of the following has been posted before, forgive me.

Written by Lord Byron, 'Lochnagar' was first published, as 'Lachin y Gair' in Byron's first [privately] published poetry collection, 'Hours of Idleness' (1807). Below are the original lyrics from that book.

Away, ye gay landscapes, ye gardens of roses!
In you let minions of luxury rove;
Restore me the rocks, where the snowflake reposes,
Though still they are sacred to freedom and love:
Yet Caledonia, beloved are thy mountains,
Round their white summits though elements war;
Though cataracts foam, 'stead of smooth-flowing fountains,
I sigh for the valley of dark Lochnagar.

Ah! There my young footsteps in infancy wandered,
My cap was the bonnet; my cloak was the plaid,
On chieftains long perished, my memory pondered,
As daily I strode through the pine covered glade;
I sought not my home, till the day's dying glory,
Gave place to the rays of the bright polar star,
For fancy was cheered by traditional story,
Disclosed by the natives of dark Lochnagar.

'Shades of the dead! Have I heard not your voices,
Rise on the night-rolling breath of the gale?'
Surely the soul of the hero rejoices,
And rides on the wind, o'er his own highland vale;
Round Lochnagar, while the stormy mist gathers,
Winter presides in his cold icy car,
Clouds there encircle the forms of my fathers,
They dwell in the tempests of dark Lochnagar.

'Ill-starred, though brave, did no visions foreboding
Tell you that fate had forsaken your cause?'
Ah! Were you destined to die at Culloden,
Victory crowned not your fall with applause;
Still were you happy in death's earthly slumber,
You rest with your clan in the caves of Braemar,
The pibroch resounds to the piper's loud number,
Your deeds on the echoes of dark Lochnagar.

Years have rolled on Lochnagar since I left you,
Years must elapse e'r I tread you again,
Nature of verdure and flowers has bereft you,
Yet still you are dearer than Albion's plain;
England! Thy beauties are tame and domestic,
To one who has roved on the mountains afar,
Oh! For the crags that are wild and majestic!
The steep frowning glories of dark Lochnagar!

The book also contained the following notes on the lyric, presumably by Byron.

'Lachin y Gair', or as it is pronounced in the Erse [Gaelic], Loch na Garr, towers proudly pre-eminent in the Northern Highlands near Invercauld. One of our modern tourists mentions it as the highest mountain, perhaps, in Great Britain. Be this as it may, it is certainly one of the most sublime and picturesque among our 'Caledonian Alps'. Its appearance is a dusky hue but the summit is the seat of eternal snows. Near Lachin y Gair I spent some of my early life, the recollection of which has given birth to the stanzas.   

Of the 'ill-starred, though brave' verse, Byron wrote,

'I allude here to my maternal ancestors, 'the Gordons', many of whom fought for the unfortunate Prince Charles, better known by the name the Pretender. This branch was nearly allied by blood as well as attachment to the Stuarts. George [Gordon], the second Earl of Huntley [sic], married the Princess Arabella Stuart, daughter of James the First of Scotland. By her he left four sons. The third, Sir William Gordon, I have the honour to claim as one of my progenitors'.

Regarding the song's stirring melody, the nineteenth century musician John Greig wrote,

'The melody set to Byron's song first appeared in vol. VI of R.A. Smith's, 'Scottish Minstrel' [1824]. Though somewhat exacting to the singer, it has met with well-earned popularity. Its composer was Mrs. Patrick Gibson, née Isabella Mary Scott, [1786-1838], who was born in Edinburgh and [who was] distantly related to Sir Walter Scott…she at one time kept a ladies' boarding-school in Inverleith Row, Edinburgh. [She] was an accomplished harpist and cultivated the society of 'litterateurs'.