M. William Sheehan?

My name is Richard Caroll Sheehan.

My father's name was Carroll Joseph Sheehan.

My grandfather's name was Joseph Carroll Sheehan.

I'm pretty sure my paternal great grandfather was M. William Sheehan, but I know very little about him. He was probably born in Ireland about 1839. I believe he married Mary J. Carroll in DesMoines Co, IA in about 1860.

I'd be very pleased for any information related to M. William Sheehan.