Archibald was the illegitimate son of Sir James "the Black" Douglas, Robert the Bruce's trusted lieutenant, and an unknown mother.

"[2] Jean Froissart in his chronicle describes Douglas, as an adult, as a large man capable of wielding a huge sword.

It has been suggested that the young Archibald spent time with his cousin William at the court in exile of King David II at Château Gaillard in Normandy.

Archibald had accompanied his cousin, William, Lord (later Earl) of Douglas, to serve John II of France in his wars against the Edward the Black Prince.

Edward III of England had concluded truce negotiations with the Scots lasting from 25 March until Michaelmas, following the Burnt Candlemas of 2 February.

Ramsay retorted, "Not he, I tell you, he is a scullion and a rogue", then to Archibald, "Go you rascal, and seek your master's body amongst the slain, so that we may at least give him a decent burial".

Since the death of Joanna's first husband, Sir Thomas de Moravia, the Lord of Bothwell, in 1361, she and her widowed mother had been wards of the court.

The first of these was to protest against the appeal launched by the newly divorced Queen Margaret at the court in Avignon of Pope Urban V. The second embassy was to Paris, with a view to renewing the Auld Alliance.

In 1369, Archibald had been appointed Lord of Galloway by King David, "becaus he tuke git trawell to purge the cuntrey of Englis blude".

Galloway had distinctive laws and customs and, as with the Kingdom of the Isles, did not feel subservient to the Scottish crown, but rather to its ancient kings, of which the Balliols were seen as representing.

In 1378, Alexander Ramsay of Dalhousie, a nephew of Archibald Douglas, took Berwick by surprise with 50 men, and was immediately besieged by the town's governor Thomas de Musgrave.

Douglas and Lord Lyndsay of the Byres assembled a relief army at Haddington, little more than 500 in number, but marched anyway, hoping to collect more men on the way.

It is around this time that Archibald started work on his fortalice at Threave Castle, and endowed Sweetheart Abbey, near Dumfries, with a hospital.

In territorial possessions alone Archibald, Lord of Galloway appeared now to have matched, if not overtaken, his cousin William, 1st Earl of Douglas.

Archibald appeared to have strengthened his line's connection with that of the Royal Stewarts, when in 1390 he arranged the marriage of his son and heir, Archibald, Master of Douglas, to Princess Margaret, and in 1399 his daughter Marjorie to David Stewart, Duke of Rothesay; both of these spouses were children of Robert III, Rothesay being the heir apparent to the throne.

Rothesay had already contracted to marry Elizabeth Dunbar, daughter of George I, Earl of March, who had paid a large sum for the honour.