Hello, a few mistakes there in the song lyrics. This is the version i use which makes a bit mor sense:
1) It was you who first plunged in and swam the shannons boiling flood
And through Slieve-Bloom's (mountain range in Tipperary) dark passes, you led your Gallowglasses (big mercenary's of scottish origin)although the hungry Saxon wolves were howling for your blood
2) And drove a 'creacht'(irish for a herd of cattle) before them as their horsemen onward came
With sword and speer we gore them, as through flood and fire we'd worn them....

P.B.