OSSIAN or OISIN is a legendary character in Gaelic literature. He figures in a series of heroic or romantic tales of which the events are laid in the third century, in the time of Cormac Mac Art [see Cormac]. According to these tales, he was the associate of Fionn, of Caillte, of Diarmait, and other warriors at the court of Tara. After many exploits, nearly all the warriors under Fionn are defeated and slain at the battle of Gabhra in co. Meath (A.D. 283). Oisin and Caillte are, however, represented as outliving the battle by 150 years. On this supposition they are credited by the professional story-tellers with meeting St. Patrick, and with relating to him, in the course of a peregrination through Ireland, the great deeds in battle or chase of their old associates. They are finally baptised, and die.
The most famous tale of the series that has survived is the 'Colloquy of the Ancients' ('Agallamh na senorach'), which is found in the 'Book of Lismore,' a late fifteenth-century manuscript, and has been edited and translated by Mr. Standish Hayes O'Grady. The 'Story of Oisin in the Land of the Young' is another extant tale of the series, and here Oisin is presented as living long underground in fairyland. The 'Book of Leinster,' a manuscript of the twelfth century, is the earliest in which any verses are attributed to Oisin. 'Leabhar na h-Uidhri,' a manuscript dating from the beginning of the same century, is the earliest in which any tale with Fionn as its hero appears. The tales are to be found in a great many later manuscripts, from 1400 onwards. Prefaces or introductions were added at various periods, but they harmonise with the literary features of the original series.
In 1762 James Macpherson [q. v.] published a poem called i Fingal,' which he pretended to have translated from Gaelic verse written by Ossian. Another volume followed in 1703. Fingal, as the name of a hero, is unknown to Gaelic literature before the time of Macpherson, and in his treatment of Fingal's exploits Macpherson shows a complete ignorance of the genuine poetic literature of the Gael. In none of the genuine Gaelic tales are Oisin and his companions associated, as in Macpherson's poems, with Cuchullin, with Fergus, with King Conchobhar, or Queen Medbh, whose exploits are placed in Gaelic literature in the first century of the Christian era. In Macpherson's 'Ossian' Fingal appears as a great Caledonian monarch disputing the conquest of his country with the Romans in the third century ; afterwards Macpherson's Fingal assists Cuchullin, who lived in the first century, to expel from Erin the Norsemen, who are known not to have approached that territory till the ninth century. Macpherson, in his so-called translation, is thus guilty of blunders which convict him of lack of all direct acquaintance with the literature from which he professed to derive his poems. The Gaelic heroes were often represented by the bards as singing their own deeds ; and in this way some poems came to be ascribed to Oisin. But it is improbable that Ossian or Oisin was the author of any of them. Poems are first ascribed to him in twelfth-century manuscripts. The Positivists have placed Oisin in their calendar, and Macpherson's publications have led to a general belief in his existence as a great Gaelic poet of remote antiquity; but whoever reads the Ossianic tales, as they are called, beginning with the preparatory ones in 'Leabhar na h-Uidhri,' and going on to those in the 'Book of Lismore,' and finally to the modern versions from 1500 to the latest Gaelic manuscripts, will be convinced that Oisin, like Fionn, must be regarded as a character of historical romance, and not as an author belonging to literary history.
[Hennessey's letters in the Academy, 1873, the publications of the Ossianic Society of Dublin (6 vols.), MacLauchlan's Book of the Dean of Lismore (the notes by Skene are of no value, as he was ignorant of Gaelic), and O'Grady's Silva-Gadelica may be consulted. See also the Highland Society's Gaelic Version of the Poems of Ossian, as published by Macpherson in English in 1762-3, 1807; The Poems of Ossian (with dissertation and translation by the Rev. Archibald Clerk), 1870; Windisch's Irische Texte, 1880, and Die altirische Sage und die Ossianfrage, 1878, Leipzig; Bailey Saunders's Life of Macpherson, 1894, and art. Macpherson, James.]