I recently came a across a reference to this song in the memoirs of a fella by the name of William Grattan who served as an Anglo-Irish officer in Spain over troops from the West of Ireland (The Connaught Rangers). The year was 1812.

I was moved by the following account of the mood of the Irish as they were preparing to rush into a brutal breech in the walls of a city called Badajoz near the borders of Portugal. Here's Grattan's words:

"The band of my corps, the 88th, all Irish, played several airs which exclusively belong to their country, and it is impossible to describe the effect it had upon us all; such an air as "Savourneen Deelish" is sufficient, at any time, to inspire a feeling of melancholy, but on an occasion like the present it acted powerfully on the feelings of the men: they thought of their distant homes, of their friends, and of bygone days. It was Easter Sunday, and the contrast which their
present position presented to what to what it would have been in their native land afforded ample food for the occupation of their minds..."

I went and found the air in O'Neill's (Number 309; page 54), and asked my wife played it for me on the Paolo, but, it being a big week last week, we didn't dig into it.   Thank you for posting these lyrics.