The founder of the family of Dunnyveg, which played so prominent and distinguished a part in the annals of the Clan Cholla, both in Scottish Highlands and in Ireland, was Iain Mhoir or, as his name was written in English, John Mor, the second son of John, Lord of the Isles by his marriage with the Princess Margaret Stewart of Scotland, daughter of King Robert the Second. Translated into modern parlance, his name was Big John. This group became known in Celtic Scotland as Clan Iain Mhoir or Clan Donald South. Iain Mhoir's father, John, Lord of the Isles, bestowed on him 120 merklands in Kintyre, the rocky peninsula of Scotland which approaches nearest to Ireland, with the castles of Saddel and Dunaverty and 60 merklands in Isla, with the castle of Dunnyveg.
A portion of this rocky promontory was later called "Connal" after Alexander Connal, Chief of the Clan Iain Mhoir.
It is mentioned by Sir Walter Scott in "The Lord of the Isles," first canto, eighth stanza, as follows:
"And listening to its own wild wind
From where Minarry strenly placed
O'erawes the woodland and the waste
To where Dunstaffnage hears the raging
Of Connal with his rocks engaging."
This place may have been used for the location of a church or as the burial place for the Chiefs of Dunnyveg, for we find it named "Kilmaconnel" in the fourth canto, twelfth stanza, of the same poem as follows:
"Up Tarbat's western lake they bore
Then dragged their bark this isthmus oer
As far as Kilmaconnel's shore."
The possession of so large a territory elevated John Mor, on the very threshold of his career, to a position of great prominence in the Highland polity and in due course he became a leading actor in the island drama.
Like all his ancestors, John Mor Tanistear was a haughty independent chief. His dominating policy was to preserve the independence of the Western Gael from aggression from the throne of Scotland. With this in mind he entered heartily into the Anglo-Scottish quarrel on the English side.
That quarrel had come to a crisis in the summer of 1388 and only a few days before the sanguinary engagement at Otterburn, John Mor Tanistear and his brothers Godfrey and Donald were received at the English Court by King Richard II. On the 14th day of July, the brothers entered into a friendly alliance with the English King, which was renewed again and again in the course of the following years.
Not long after his reception at the English Court, John Mor Tanistear married Margery Bisset, heiress of the Glens in Antrim, Ireland. The Bissets, who were of Greek extraction, came over to England with William the Conqueror and settled after a time in Scotland. Before the close of the 13th century they had acquired the seven lordships of the Glens in Antrim. Through his marriage with Margery, the only daughter of John Bisset, the last male head of this family, Iain Mhoir Tanistear succeeded to the heritage of the Glens, extending from the Inver to the Boyse. From this time onwards he and his successors were styled "Lord of Dunnyveg and the Glens." The addition of this large territory in Ireland to his possessions in Argyle, Scotland, elevated him into the position of a magnate of the first importance.
On the death of Richard II of England, John Mor Tanistear and his brother transferred their alliance to that King's successor, Henry IV. Twice during the year 1400 they visited his court and in the year 1408 John Mor Tanistear is again found visiting his court.
In the struggle between the Lord of the Isles, nephew of Tanistear, and the Regent Albany in 1411, Iain Mor Tanistear had his full share. On the day of Harlaw which proved so disastrous to the Regent's hosts, John Mor Tanistear at the head of the reserve, contributed largely to the vistory of the men of the Isles. When the Regent afterward followed the Lord of the Isles into Argyle the resolute Tanistear again came forward to strike a blow for his race and Albany was repulsed.
The Scottish King finding he was unable to defeat Tanistear in battle, laid a trap for him. He sent James Campbell to arrange the details. In the words of the Sleat Seanachie: "John (Mor Tanistear) came to the place appointed with a small retinue, but James Campbell, came with a very large train. James told him of the King's intention of granting him all the lands possessed by the Macdonalds if he would join him in an attack on the other Macdonalds. John said he did not know wherein his nephew wronged the King and that his nephew as as deserving of his rights as he could be and that he would not accept of these lands, nor serve for them, till his nephew would be set at liberty; and that his nephew himself was as nearly related to the King as he would be. James Campbell, hearing the answer, said he was his prisoner. John made all the resistance he could, till, overpowered by numbers he was killed." Campbell was later executed for this murder, protesting however, that it was done under the King's order. Iain Mhoir Tanistear as Chief of Clan Donald South was succeeded by his eldest son, Donald Ballock.