[From Nisbet's Heraldry; Burke's Peerage and Celtic Scotland]
ANGUS, the older name of the County of Forfar [now restored], was the territory of one of the great Pictish tribes or sub-kingdoms, and was governed by a succession of Celtic maormors.
The Pictish Chronicle furnishes us with the names of three, viz.
INDRECHTAIG, who flourished about the year 900. His son
DUBUCAN, died about 935, and had a son named
MAELBRIGDI, perhaps the Maelbrigdi of the Saga; after him the next record of a ruler of Angus is
DUFUGAN Comes, one of the seven Earls of Scotland appearing in the reign of Alexander I. The similarity of the name to that of the second maormor justifies the allocation of this Earl to the Angus line. After him comes a succession of five Earls from father to son, first of whom is
GILLEBRIDE, who fought at the battle of the Standard in 1138, and about 1160 witnessed a charter of Malcolm IV to the Monastery of Dunfermline. In 1164 he and Adam his son attest a national document. Gilbert, son of this Earl, acquired the lauds of Ogilvie, and is reputed ancestor of the Ogilvies, Earls of Airlie, Findlater, Seafield, and Lords Banff. Earl Gillebride was succeeded by his eldest son
GILCHRIST, who first appears opposing Somerled, Thane of Argyll and the Isles. That ambitious chief had made war against the authority of Malcolm IV After various conflicts Somerled was repulsed, though not subdued, by Earl Gilchrist, and the peace concluded with this powerful chieftain in 1153 was considered of such importance as to form all epoch in the dating of Scottish charters. History of the Scottish Clans
A still more formidable insurrection broke out in Moray under Gildominick, on account of the attempt to intrude in that county the Anglo-Norman jurisdiction of the Lowlands on their Celtic customs, and the settling of Anglo-Belgic colonists among them. These insurgents laid waste the neighbouring counties, and so regardless were they of the royal authority, that they actually hanged the heralds sent to summon them to lay down their arms. King Malcolm despatched the gallant Earl Gilchrist with an army to subdue them, but he was defeated and forced to recross the Grampians (circa 1160). [From Nisbet's Heraldry]
Gilchrist was one of the hostages for King William the Lion in 1174. His seal appended to a charter of his to the monastery of Dunfermline shows on the helmet a flourishing branch of a palm tree, which is the earliest instance in Scotland of a shield being timbered with helmet and crest. [From Nisbet's Heraldry]
He is stated to have married Mauld, a natural daughter of King Malcolm and sister of Duncan. To him succeeded
GILLEBRIDE, who about 1180 witnessed a charter of King William the Lion to the Abbey of Aberbrothock. His son William appears ante 1200 in the Arbroath Chartulary, and another son Angus 23rd September, 1219, in the Acts of Parliament. He is stated to have married, first, a daughter of Patrick Dunbar Earl of March and secondly, the heiress of John, 30th Earl of Orkney and Caithness. He had issue:
MALCOLM (1225-1242), the last Earl of this Celtic line. A fac-simile of his seal appears in Laing's Catalogue (Number 420). A charter of King Alexander II to the Chapel of St. Nicholas at Spey, dated 2nd October 1232, is witnessed by M...., Earl of Angus and Caithness. Magnus, son of the Earl of Angus (second son of Earl Gilbride), who was present at the perambulation of the Aberbrothock Abbey boundaries, 16th January 1222, is taken to be the first of the Angus line Earls of Orkney. Earl Malcolm married a daughter of Sir Humfrey Barclay, and died circa 1237, leaving a daughter [From Nisbet's Heraldry]
MATILDA, Countess of Angus in her own right, who married, first, John Comyn, Earl of Angus by right of his wife. Dying in France in 1242, he left an infant son, BERTRALDE, Master of Angus, who followed his father to the grave the same year. In 1243 the Countess Matilda married Sir Gilbert Umfraville, thereupon designated Earl of Angus, and by him (who died 1245) had
GILBERT UMFRAVILLE, Earl of Angus, noted as in ward 1264, and a year or two later as of age. He was a prominent person in the wars of the Scottish succession, and, in 1291, commanded the important Castles of Dundee and Forfar, which he declined to surrender to Edward I of England until he received a formal letter of indemnity from the Estates of Scotland. [From Tytler]
After the forfeiture of the Umfravilles, the Earldom was conferred on John Stewart of Bonkill, whose granddaughter Margaret resigned the Earldom in 1389 in favour of her natural son George, by William, first Earl of Douglas and Mar, who thus became founder of the Douglas line and ancestor of all subsequent Earls of Angus, Marquises and Dukes of Douglas, and Dukes of Hamilton, etc., etc. The descendants of the Umfravilles are the representatives of Matilda, Countess of Augus, while the representation of the male line devolved on Malise, Earl of Stratherne, who, about 1321, succeeded Magnus of Angus, last of his line, Earl of Orkney.
In Balfour's Annals Prince David, Earl of Huntington, is described as also Earl of Angus from 1170 to 1205.