KA^K—T/ie Black Pig's Dyke. 311 



can be attached to the designation except as a reflection of the ordinary belief 

 that all ancient works of the kind were Danish — a supposition which we know 

 to be without warrant. 



Nor do we find that the title is applied to any similar fragment elsewhere 

 in the country, except in the case of a short line of trench south of Armagh, 

 near Lisnadill, while the designation of the " Black Pig Valley " is recog- 

 nized throughout the whole of its course, sometimes in conjunction with 

 alternative local designations. Now, if the Dane's Cast was a local defensive 

 boundary without connexion with the Worm Ditch, &c., against whom could 

 it have been erected ? Canon Lett and other antiquaries have hitherto put 

 forward the view that it was " The Great "Wall of Ulidia," and was made to 

 confine the Ulster men, when after the battle of Acaidh Leithdearg in Earney, 

 Co. Monaghan, and the burning of Emania by the three Collas in 332, they 

 were driven into the territory thenceforth called Ulidia.^ This comprised 

 the present Counties of Down and Antrim. O'Donovan was at first of this 

 opinion, and in a note in his translation of the Book of Eights^ speaks of 

 Glenree or the Newry Valley " through which an artificial boundary was 

 formed, now called the Dane's Cast." This boundary, he goes on to say, is 

 distinctly referred to in a manuscript in the Library of Trinity College, 

 Dublin (H. III. 18, p. 783), in the following words : — " On the hither side of 

 Gleann Kighe, the boundary of Gleann Kighe was formed from the Newry 

 upwards between them (i.e., the Clann Collaandthe Clanna Rudhraighe), and 

 the Clanna Rudhraighe never returned across it from that time to the 

 present." It is to be observed that this statement does not specify an 

 artificial structure, but may be read as a geographical delimitation of the 

 confines. However that may be, further inquiry led O'Donovan, as we 

 shall see, to abandon this explanation of its origin. Moreover, the chief 

 difficulty in accepting this hypothesis arises from the futility of the work as 

 a defence against the defeated race of Ultonians, or as a means of confining 

 them to the limits of Down and Antrim. For it seems plain that to effect 

 this it should have commenced at such part of the Newry River as is too 

 broad for an armed body of men to have crossed by swimming — a well-known 

 method in those days — and should have continued along the bank of that river 

 northward by the boundary of Ulidia to Lough Neagh, and thence from 

 the north shore of that lake by the Bann to the sea. 



An invading host on their march to Emania (Armagh) would scarcely 

 cross the Newry River and traverse Glen Ree exposed to flank attacks from 

 enemies in the wooded slopes that composed its western side, when, since the 



• See Map, p. 316. * Celtic Society's Publications, p. 37, uote. 



