This is what my mother used to sing 60 years ago. The Second verse somewhat different. My family had no Irish connections and we had no idea where it came from.

My uncle Micky had a stick
And he took it to the Slaughter
He killed 5000 Irish men
In the battle of Boiling Water

Some were dead and some were alive
And some were shouting’murder’
So he upped with his stick
And he knocked them sick
In the Battle of Boiling Water