Mabel asks her mother about the passing troops and their leader. Mother answers that the men are the Volunteers and Grattan their leader. "They rose to guard from foreign foes, as well from British guile" Witness "the baffled hosts of Gaul"
The Belfast Volunteers were formed in 1778 because of the threat of war between France and Britain. Similar groups formed, became politicized, and supported "those in favour of legislative independence from the British parliament and the removal of impediments to Irish commerce." Henry Grattan and Harry Flood supported this program in the Irish House of Commons. (Source} Moylan)
O'Conor shows the author as "M.O.B." I posted an inquiry for speculation as to who "M.O.B." might be. John Moulden -- researcher at the "Centre for the Study of Human Settlement and Historical Change" at National University of Ireland, Galway, whose subject is "the printed ballad in Ireland" -- gave me two leads. First, he pointed out that Hayes (see ADDITIONAL, above) -- possibly O'Conor's source -- has the author as "M.O'B" and that another good resource might be David James O'Donoghue, _The Poets of Ireland: a Biographical Dictionary_ (O'Donoghue, 1892-3). One possibility in O'Donoghue is O'Brien, M.E., a "very frequent contributor of verse to _Sentimental and Masonic Magazine_ of 1794-5.... He may have been the 'O'B' of _Sentimental and Masonic Magazine_ 1794." (p. 180). - BS
For more on Grattan, see e.g. "Ireland's Glory." For the Volunteers, see among others "The Green Cockade," "The Shamrock Cockade," and "The Song of the Volunteers."
The reference to the "baffled hosts of Gaul" makes me think this might refer to a period somewhat after Grattan's great success (which Ben's research on the author indirectly supports). This sounds as if it might come from around the period of the French failure at Bantry Bay -- when Grattan's parliament was functioning but before the 1798 rebellion. - RBW