The song is in The Poets and Poetry of Ireland (1881), with an introductory paragraph:
The following spirited and humorous "lament" is taken from "The Banks of tbe Boro," by Patrick Kennedy, a story which gives with remarkable faithfulness and minuteness the incidents of Irish country life. It is given with a number of other specimens of peasant poetry.

Nowadays it tends to be sung straight, but humorous elements are there to see: "dirty king"; piper blowing the fire with his bellows; valiant boy in trouble with the peelers. Some of the language might be a caricature of country style ("pathriarchs", "throunce the buckeens... bekase our eyes"). Perhaps there's also a question of why Ireland's pride was dependent on war in the foreign land of Spain.