rockfort rock

What exactly was the function of his unit - "Engineers"? Would it be the same as a regular military unit of engineers?

It is very unusual to see a unit designation like "Engineers", the normal description was just x Battalion, y Brigade. In the context of the Anglo Irish War IRA, engineers would possibly have been bomb makers or else blokes who dug up roads to create barricades etc.

I hope my first post is of interest here.

I've taken excerpts from my maternal Grandfather's Military Service Pension Application form.

They clearly support Paul L Murphy's description of 'Engineers' from this period. Also they show, in this particular case, 'Engineers' to be a small unit within my Grandfather's company, going on to form a larger body at Battalion or Brigade level.