I've found this Boys of The Irish Brigade. I'm not sure that this is the one but if you want the Boys Of the Old Brigade Chords, here goes in C.

(C) What for should I sing you of (F)Roman or Greek,
Or the (C) boys we hear tell of in (G) story?
Come (C) match me for fighting, for (F)frolic, or freak,
An (C) Irishman's (G) reign in his (C) glory;
For (G) Ajax, and Hector, and bold Agamemnon,
Were (C) up to the tricks of our (G)trade, O,
But the (C) rollicking boys, for war, (F)ladies and noise,
The (C) boys of the (G) Irish Bri(C)gade, O!

What for should I sing you of Helen or Troy,
Or the mischief that came by her flirting?
There's Biddy M'Clinchy the pride of Fermoy,
Twice as much of a Helen, that's certain.
Then for Venus, so famous, or Queen Cleopatra,
Bad luck to the word should be said, O,
By the rollicking boys, for war, ladies and noise,
The Boys of the Irish Brigade, O!

What for should I sing you of classical fun,
Or of games, whether Grecian or Persian?
Sure the Curragh's the place where the knowing one's done,
And Mallow that flogs for diversion.
For fighting, for drinking, for ladies and all,
No time like our times e'er was made, O,
By the rollicking boys, for war, ladies and noise,
The boys of the Irish Brigade, O!