The anonymous exile's most famous work is a fragmentary Latin eclogue praising Charlemagne for his defeat of Tassilo III of Bavaria in 787.
The poem, Ad Karolum Regem (To King Charles) in the Monumenta Germaniae Historica and In Praise of Poetry in Peter Godman's excerpted English translation, is written as a dialogue between poet and Muse (the parts of which are diffictult for modern editors to perfectly discern), an idea picked up by Walahfrid Strabo.
The poem begins with a description of Charlemagne and Tassilo, dux inclitus (distinguished duke). Charlemagne's gifts to the disobedient Tassilo, Tassilo's ceremonious submission and payment of tribute, and the reconciliation of the two Christian princes are the major themes of the opening part of the work. The remainder is filled by the dialogue of the humble poet with nothing of great worth for the king and the Muse who shows him the immortality of poetry.
To the historian, the exul's poem indicates the high value ascribed to generosity and reconciliation amongst Christians and portrays the defeated duke in a fair light. The exaltation of poetry (by a poet) was necessary in a world that concentrated on material and especially martial success. The poet also affirms that secular subjects are equally worthy as sacred ones for versification; one of the earliest Latin Christian defences of courtly/public panegyric.
Read more about this topic: Hibernicus Exul