The singer married a sailor/soldier and now wanders disowned by her parents, "Alone on the Shamrock shore" with her baby. Called to fight, her husband has a disagreement with his superior and is hanged/whipped.
Alone on the Shamrock Shore (Shamrock Shore III) Partial text(s) *** A *** From Kenneth Peacock, Songs of the Newfoundland Outports, Volume II, pp. 418-419. Sung by Mary Ann Galpin, Codroy, July 1960. Come all you fair maids take a warning, With a handsome young stranger don't wed, Try all that you can for to slight him, Or banish him out of your head, For once I lived light-hearted and cheerful, Such pleasure I never had before, But now I am lief for to wander Alone on the shamrock shore. (Three additional stanzas plus a half stanza.)
The Bodleian broadsides "Shamrock Shore"/"Shamrack Shore"/"New Shamrock Shore" replaces the sailor by a soldier, the "trifle dispute with his captain" becomes a "small dispute with a serjeant" at Lifford and the war, if specified, is against "the bold rebels"; "Disdained Daughter..." retains the sailor, the war is with Spain and the incident is at Portsmouth [as in Peacock's version]; in all broadsides the hanging is a lashing, father's castle is a "snug neat little cottage...." Perhaps the "New" title indicates that the sailor version is the older. - BS
To add to the fun, the whole thing reminds me strongly of "The Gallant Hussar (A Damsel Possessed of Great Beauty)," though there don't seem to be many direct allusions. - RBW