There might be a couple of songs that exist about them.

The particular song I'm looking for contains the following verses. I'm not sure how many more verses are in the song, but years ago I remember browsing at a song about them that contained about ten verses.

'Once again the blood of martyrs
flows upon the scaffold high
once again the vengeful tyrant
has decreed that men must die
stricken in their early manhood
blasted by her cruel hate
side by side upon the scaffold
England's lust for blood to seed'

'Martyred for their love of Ireland
murdered by their ancient foe
could they rise from out of the ashes
they would strike another blow
mourn them with such dauntless courage
only to the brave belong
god rest you soldier sons of Ireland
gone to join that gallant throng'

'They shall never be forgotten
in the land that gave them birth
though their lifeless clay be lying
far away from Irish earth
they shall come to speed the dawning
when from their ashes they'll arise
Peter Barnes and James Mc Cormack
for our sake they have lived and died.'