It occurs to me that this might be an anti-enlistment song? Saying it's better to emigrate than join the British army?

Especially

May bad luck shine down on those Red Hats of Ireland,
Who want me to work for sixpence a day.

and

Come all you young fellows, from me take a warning,
From your home to a Red Hat let you never stray,
For if you get sick you are wanting no longer,
You may go to the Union or else get away.