Thanks; the foregoing agree with the verses found so far, and with the comment I made earlier about the Library of Congress (LoC.). Unfortunately, the copy from Cork only appears to show one chorus, apart from after the final verse, and is (as for the LoC.version) undated.
The Library of Congress version is a printed songsheet (clearer than the Cork version) But, using the LoC. version means we need to consider their other holdings, and (in trying to date the songsheet by comparison with others by the same publisher) I found the following.

12TH REGIMENT,
NEW-YORK STATE MILITIA.
AIR: Viva la.--By Archibald SCOTT

The gallant Twelfth where e'er they go,
Are sure to rout the Rebel Foe,
For Stars and Stripes they'll strike a blow.
Will make the traitors yield.
Our cause baptized in Martyr's blood,
Who for their country nobly stood,
Shall be preserved by yeomen good,
With gallant Butterfield.

Chorus: Viva la for freedom's right,
Viva la for freedom's wrong,
Viva la to shades of night,
We'll sweep the southron rebel throng.

Our fathers brave, who fought and died
For that dear flag, our joy and pride
Did this grand sacred trust confide
To us for to maintain;
Then shall we see it in the dust,
And let our swords in scabbards rust?
No! by that Heav'n in which we trust,
With life we'll it sustain.

Chorus: Viva la the twelfth Brigade,
Viva la for Stripes and Stars,
Viva la the South shall fade
Before our Northern sons of Mars.

Another year shall not pass by,
Ere Davis shall, like Haman high,
On his own gallows dog-like die,
A traitor's fearful doom.
There's Twiggs and Beauregard yet shall rue
Their baseness to white, red and blue,
To Stephens Floyd and all the crew
We'll give an Arnold's tomb.

Chorus: Viva la for Butterfield,
Viva la for his command,
Who'll make SLAVISH rebels yield,
And sweep them from our glorious land.

There's not a man now by him led,
Who would not dare his blood to shed
For rights for which so many bled,
Of freedom's bravest sons.
The South will soon have work to do,
Their boasting we shall soon subdue,
Our Soldiers all are white men true,
Well skill'd with swords and guns.

Chorus: Viva la for General Scott,
Viva la for Lincoln too:
The Southron rebels' bones shall rot
E'er we shall lower white, red and blue.


H. DE MARSAN, Publisher.
Songs, ballads, toy-books.
60 Chatham str. New-York.

Obviously, there is a similarity in Metre, scansion, and rhyme scheme. Also the choruses follow an almost identical pattern.

The question now is, which is original, and which derivative (or, is either original!) ? Looking at the addresses given for the publisher, we see that he has moved premises on Chatham St. (or the street has been re-numbered.).
The songsheet for "Clare's Dragoons" clearly shows a change of address suggeting that this was published later than the song of The Twelth Regiment (publication date may not be related to date of writing) The address change has been made (apparently) by chiseling out the original street number, and replacing it with new type.
Also, the Song of The Twelfth is quoted as by "Scott, Archibald" and to the tune of "Air: Viva la - by Archibald Scott"
I thought I was starting with a simple correction for a DTStudy !!! How mistaken I was !

Nigel