7Rogers, R.S. "The Folklore of the Black Pig's Dyke." Ulster Folklife 3.1 (1957): 30-31.
The author notes, "This story has the authentic ring of myth and it is so well diffused throughout the length of the three frontiers in association with the rampart that I have taken it as the basic story."
The genesis of the legend may have been a narrative found in "The Tale of the Fate of the Children of Tuireann," one of the three "Sorrowful Tales of Erin," where Cian, Father of Lugh, changes himself into a Druidical pig and begins rooting up the earth to save himself from the three sons of Tuireann, who wish to kill him. Two of the sons of Tuireann, however, are magically transformed into hunting dogs, and they pursue the man-pig into a grove of trees, where the third brother flings a spear at him and kills him.
Here are the outlines of some variants to the basic story, taken from the Rogers article and from others listed below:
Occasionally it is the mother and not the father of the boy that changes the schoolmaster into the pig.
Sometimes the story is concluded with the prophecy that there will be war in the valley of the Black Pig. This is dealt within in some detail toward the conclusion of the essay.
Kane (1908) recorded this variation: "...the three sons of Tureann resolved to take revenge on the Druid [schoolteacher]; and on the occasion of his changing himself into a black pig pursued and killed him near Cnoc-Cian-mic-Cainte, sometimes called Killeen Hill, which is north of Dundalk; and Cian's grave was seen on the hill till about 1836, when a farmer named Dickie tore it down..."
Kane also recorded a version, near Granard, that inserts St. Patrick into the narrative: "When, however, the form of a black pig was assumed, St. Patrick took fresh courage, and, following the deep track or furrow that it left behind, succeeded at length in running it down at Granard, where the animal was killed, and the demon no more disturbed the countryside by his apparition."
Brian Sherry (1993) noted that "It was also widely believed in mid-Monaghan that before the end of the world The Black Pig would return and flatten the Dyke again."
Fionnuala Williams (1978) noted that: "Other methods of preventing the schoolmaster from changing himself back into human form were by closing or burning his book. An alternative to all these was to procure special hounds such as a pup of the first litter or a pure black bitch with no rib of white hair and simply lie in wait for the schoolmaster when he was out hunting with his pupils. He could also be shot with silver: pure black dogs and pure silver were believed to have the power to overcome supernatural beasts.
Our virtual-reality work in the area of Kiltycloger near where this story was collected was completed with the assistance of guidebook author Anthony Weir. Here is a photograph of three of the four members of the group: Anthony Weir, Malcomb Walker, and Robin Goldbaum (July 15 2013).