John Mór Tanister was the second son of John Macdonald

John of Islay, Lord of the Isles

John of Islay was the Lord of the Isles and chief of Clan Donald. In 1336, he styled himself Dominus Insularum, "Lord of the Isles"; because this is the first ever recorded instance of the title in use, modern historians count John as the first of the later medieval Lords of the Isles, although...

 (John of Islay, Lord of the Isles) and Princess Margaret Stewart of Scotland, daughter of King Robert II

Robert II of Scotland

Robert II became King of Scots in 1371 as the first monarch of the House of Stewart. He was the son of Walter Stewart, hereditary High Steward of Scotland and of Marjorie Bruce, daughter of Robert I and of his first wife Isabella of Mar...

. He is the founder of Clan MacDonald of Dunnyveg

Clan MacDonald of Dunnyveg

Clan MacDonald of Dunnyveg, also known as Clan Donald South, Clan Iain Vor, Clan MacDonald of Islay and Kintyre, MacDonalds of the Glens and sometimes referred to as MacDonnells, is a Scottish clan and a branch of Clan Donald...

.

He was granted 120 merklands in Kintyre

Kintyre

Kintyre is a peninsula in western Scotland, in the southwest of Argyll and Bute. The region stretches approximately 30 miles , from the Mull of Kintyre in the south, to East Loch Tarbert in the north...

, with the castles of Dunaverty

Dunaverty Castle

Dunaverty Castle is located at Southend at the southern end of the Kintyre peninsula in western Scotland. The site was once a fort belonging to the Clan Donald . Little remains of the castle, although the site is protected as a scheduled monument....

, Skipness

Skipness Castle

Skipness Castle stands on the east side of the Kintyre Peninsula in Scotland near the village of Skipness.-History:The main structure of the castle was built in the early 13th century by the Clan MacSween with later fortifications and other additions made to the castle through the 13th, 14th and...

 and Airds

Airds Castle

Airds Castle is a ruined castle near Carradale, Kintyre, Argyll and Bute, Scotland. The castle held a position on the summit of a rock outcrop between Carradale harbour and the bay of Port Righ....

 and 60 merklands on Islay

Islay

-Prehistory:The earliest settlers on Islay were nomadic hunter-gatherers who arrived during the Mesolithic period after the retreat of the Pleistocene ice caps. In 1993 a flint arrowhead was found in a field near Bridgend dating from 10,800 BC, the earliest evidence of a human presence found so far...

 with the castle of Dunyvaig

Dunyvaig Castle

Dunyvaig Castle, is located on the south side of Islay, on the shore of Lagavulin Bay, from Port Ellen. The castle was once a naval base of the Lord of the Isles, chiefs of Clan Donald. It was held by the chiefs of the Clan MacDonald of Dunnyveg....

 upon his fathers death. Not being satisfied with his inheritance, he led a revolt against his brother Dómhnall Íle

Domhnall of Islay, Lord of the Isles

Donald, or properly, Dómhnall Íle , was the son and successor of John of Islay, Lord of the Isles and chief of Clan Donald. The Lordship of the Isles was based in and around the Scottish west-coast island of Islay, but under Domhnall's father had come to include many of the other islands off the...

 as John was recognized as the heir-apparent (tànaiste

Tanistry

Tanistry was a Gaelic system for passing on titles and lands. In this system the Tanist was the office of heir-apparent, or second-in-command, among the Gaelic patrilineal dynasties of Ireland, Scotland and Man, to succeed to the chieftainship or to the kingship.-Origins:The Tanist was chosen from...

). The rebellion started in 1387 and went on into the 1390s, and John obtained the support of the powerful Clan MacLean

Clan MacLean

Clan Maclean is a Highland Scottish clan. They are one of the oldest clans in the Highlands and owned large tracts of land in Argyll as well as the Inner Hebrides. Many early MacLeans became famous for their honour, strength and courage in battle. They were involved in many clan skirmishes with...

 kindred. However, John and the MacLeans were eventually forced to submit to Dómhnall, and by 1395 John Mór had been forced to flee into Ireland. There he entered the service of King Richard II of England

Richard II of England

Richard II was King of England, a member of the House of Plantagenet and the last of its main-line kings. He ruled from 1377 until he was deposed in 1399. Richard was a son of Edward, the Black Prince, and was born during the reign of his grandfather, Edward III...

 in Antrim and later King Henry IV

Henry IV of England

Henry IV was King of England and Lord of Ireland . He was the ninth King of England of the House of Plantagenet and also asserted his grandfather's claim to the title King of France. He was born at Bolingbroke Castle in Lincolnshire, hence his other name, Henry Bolingbroke...

.

Through his marriage with Margaret Bisset

Margery Byset

Margery Byset was an Irish noblewoman belonging to the Bissett family whose marriage to John Mór Tanister MacDonnell in 1399 laid the basis for the Clan Donald claim to the Glens of Antrim, the lordship of which her family had established in the 13th century...

, a daughter of the MacEoin Bisset, Lord of the Glens, according to MacDonald shanachies he received as the dowry the Glens

Glens of Antrim

The Glens of Antrim , known locally as simply The Glens, is a region of County Antrim, Northern Ireland. It comprises nine glens , that radiate from the Antrim Plateau to the coast. The Glens are an area of outstanding natural beauty and are a major tourist attraction in north Antrim...

 and Rathlin Island

Rathlin Island

Rathlin Island is an island off the coast of County Antrim, and is the northernmost point of Northern Ireland. Rathlin is the only inhabited offshore island in Northern Ireland, with a rising population of now just over 100 people, and is the most northerly inhabited island off the Irish coast...

 in Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

, then becoming known as Lord of Dunnyvaig and the Glens. In fact this is a later invention, for the MacEoin Bissets continued to hold the Glens of Antrim until at least as late as 1522, when the last known died in battle.

He led the reserve at the battle of Harlaw

Battle of Harlaw

The Battle of Harlaw was a Scottish clan battle fought on 24 July 1411 just north of Inverurie in Aberdeenshire. It was one of a series of battles fought during the Middle Ages between the barons of northeast Scotland against those from the west coast....

 just north of Inverurie

Inverurie

Inverurie is a Royal Burgh and town in Aberdeenshire, Scotland, approximately north west of Aberdeen on the A96 road and is served by Inverurie railway station on the Aberdeen to Inverness Line...

 in Aberdeenshire on 24 July 1411 and later fought with Robert Stewart, Regent Albany

Regent Albany

Regent Albany can refer to several Dukes of Albany who served as regent of the Kingdom of Scotland:*Robert Stewart, Duke of Albany *Murdoch Stewart, Duke of Albany *John Stewart, 2nd Duke of Albany...

 who had forayed into Argyll

Argyll

Argyll , archaically Argyle , is a region of western Scotland corresponding with most of the part of ancient Dál Riata that was located on the island of Great Britain, and in a historical context can be used to mean the entire western coast between the Mull of Kintyre and Cape Wrath...

 to force his brother Dómhnall Íle to surrender.

John Mor was attacked and killed by James Campbell after a scheduled meeting at Ard-du, Islay in 1427.

Family

By his wife, Margaret, daughter of MacEoin Bisset, Lord of The Glens, they had:

• Donald Balloch MacDonald d. 1476, married Johanna, daughter of Conn O'Neill of Edenduffcarrick.

He is also the father of Ranald Bane MacDonald

Ranald Bane MacDonald, 1st of Largie

Ranald Bane MacDonald was the second son of John Mór Tanister and a daughter of Finnon or by his wife Margery Byset. He is the founder of Clan MacDonald of Largie...

, by a daughter of the Finnon (the Green Abbot) or by his wife Margaret.