The town and port of Dunbar has figured prominently at various points in Scottish history and the family whose name It bears is of ancient Celtic origin. Gospatrick Earl of Northumberland, received the lands of Dunbar and other parts of Lothian from Malcolm III. His son witnessed the foundation of the great Abbey of Holyrood Rouse in 1128, and was accorded the rank of earl. He made donations to the Abbey of Kelso and is recorded in various charters. Patrick of Dunbar married Ada, natural daughter of William the Lion, around 1184 and was created justiciar of Lothian. Earl Patrick' s daughter received as part of her dowry the lands of Home, establishing the line that was later to be created Earls of Home in the seventeenth century. Her brother, Patrick, went to the Crusades, and died in 1248 at the siege of Damietta in Egypt. Patrick "Black Beard", Earl of Dunbar, was one of the competitors for the Crown of Scotland at Berwick in 1291 through his royal great-grandmother, Ada. His wife was a Comyn and held Dunbar Castle for Balliol, but was forced to surrender it in April 1296. The tenth Earl, another Patrick, sheltered Edward II of England at Dunbar after his flight from the field of Bannockburn in 1314. Historians have suggested that if the king had been seized by Dunbar he might have been forced to make peace with Robert the Bruce, thereby preventing further years of bloodshed. Despite his apparent treachery, the earl made his peace with his cousin the king, and was present at the Parliament at Ayr in 1315 which settled the succession of the Scottish throne. He was appointed governor of Berwick, where he was besieged by Edward III. He surrendered to the English and the town was refortified and garrisoned by English troops. Dunbar renounced any allegiance to the English king, as a result of which his castle was besieged by the Earl of Salisbury. Command of the castle fell to Dunbar' s wife, commonly called "Black Agnes", who per-formed her task with vigour. The English attacked the castle with all the technology of fourteenth-century siege craft, and when they brought up a machine which, from its shape was called the sow' , she personally directed its destruction by rocks hurled from the castle walls. As the English fled for their lives she is said to have scoffed, "behold the litter of English pigs". The siege lasted nineteen weeks and Salisbury eventually retired, leaving Black Agnes in possession of her husband' s fortress.

The tenth Earl was one of the most powerful nobles in Scotland, with vast estates. In 1388 he accompanied the Earl of Douglas into England and fought at the Battle of Otterburn. He had arranged a marriage for his daughter with the Duke of Rothesay, son of Robert III, but through the influence of the Douglases the marriage did not take place. The earl was incensed by this slight to his family pride, and retired to his estates in England. He was eventually reconciled with the Douglases and returned to Scotland in 1409. George, the eleventh Earl, succeeded to his father' s title and vast estates in 1420, and was prominent in public affairs. His wealth, however, was to be his undoing: James I coveted the Dunbar estates and imprisoned the earl on trumped-up charges of treason, so the earldom and the estates were forfeited to the Crown. The last earl died in England in 1455.

The family had established a number of branches, including the Dunbars of Mochrum (to which house the present chief belongs), of Northfield, Hempriggs, Durn and Both. It is a tribute to the distinction of this name that each of these five branches achieved the rank of baronet. Gavin Dunbar, Archbishop of Glasgow and Lord High Chancellor of Scotland in the reign of James V, was a younger son of Sir John Dunbar of Mochrum He distinguished himself at the University of Glasgow and in 1514 became Dean of Moray In 1524 he was appointed Archbishop of Glasgow. He weathered the first storms of the Reformation and although reckoned a good and learned man, was criticised for his participation in the persecution of Protestants instigated by Cardinal Beaton. Sir James Dunbar of Mochrum was created a Baronet of Nova Scotia in March 1694 with a special royal honour of a grant of supporters "Imperially Crowned". The second Baronet served in the Duke of Marlborough' s cavalry with great distinction. He was recognised as chief on the death of Ludovic Dunbar in 1744.Sir William Dunbar, ninth Baronet, was Registrar General from 1902 to 1909. The title of the present chief was established only after a celebrated court case in 1990 first heard before the Lord Lyon, King of Arms, then appealed to the Supreme Court in Edinburgh and finally concluded in the House of Lords in London.