His grandmother, Diane d'Andouins, comtesse de Gramont, was "la belle Corisande," one of the mistresses of Henry IV. The grandson assumed that his father Antoine II de Gramont, viceroy of Navarre, was the son of Henry IV, and regretted that he had not claimed the privileges of royal birth. Philibert de Gramont was the son of Antoine II by his second marriage with Claude de Montmorency, and was probably born at the family seat of Bidache.
He was destined for the church, and was educated at the college of Pau, in Beam. He refused the ecclesiastical life, however, and joined the army of Prince Thomas of Savoy, then besieging in Piedmont. He afterwards served under his elder half-brother, Antoine, marshal de Gramont, and the prince de Condé. He was present at Freiburg and Nordlingen, and served with distinction in Spain and Flanders in 1647. He favoured Condé's party at the beginning of the Fronde, but changed sides before he was too severely compromised. In spite of his record in the army he never received any important commission either military or diplomatic, perhaps the cause of an incurable levity in his outlook. He was, however, made a governor of the Pays d'Aunis and lieutenant of Beam. During the Commonwealth he visited England, and in 1662 he was exiled from Paris for paying court to Mademoiselle de la Mothe-Houdancourt, one of the king's mistresses. He went to London, where he found at the court of Charles II an atmosphere congenial to his talents for intrigue, gallantry and pleasure.
He married in London, under pressure from her two brothers, Elizabeth Hamilton, the sister of his future biographer. "La belle Hamilton" was one of the great beauties of the English court, and was, according to her brother's optimistic account, able to fix the count's affections. She was a woman of considerable wit, and held her own at the court of Louis XIV, but her husband pursued his gallant exploits to the close of a long life, being, said Ninon de l'Enclos, the only old man who could affect the follies of youth without being ridiculous. In 1664 he was allowed to return to France. He revisited England in 1670 in connection with the sale of Dunkirk, and again in 1671 and 1676. In 1688 he was sent by Louis XIV to congratulate James II on the birth of an heir. From all these small diplomatic missions he succeeded in obtaining considerable profits, being destitute, and having no scruples whenever money was in question. At the age of seventy-five he had a dangerous illness, during which he became reconciled to the church. His penitence does not seem to have survived his recovery.
He was eighty years old when he supplied his brother-in-law, Antoine Hamilton, with the materials for his, Mémoires. Hamilton said that they had been dictated to him, but no doubt he was the real author. The account of Gramont's early career was doubtless provided by himself, but Hamilton was probably more familiar with the history of the court of Charles II, which forms the most interesting section of the book. Moreover Gramont, though he had a reputation for wit, was no writer, and there is no reason to suppose that he was capable of producing a work which remains a masterpiece of style and of witty portraiture.
When the Mémoires were finished it is said that Gramont sold the manuscript for 1500 francs; and kept most of the money himself. Fontenelle, then censor of the press, refused to license the book from considerations of respect to the strange old man, whose gambling, cheating and meannesses were so ruthlessly exposed. But Gramont himself appealed to the chancellor and the prohibition was removed. He died on 10 January 1707, and the Mémoires appeared six years later.
His biographer Hamilton was far superior to the comte de Gramont, but he relates the story of his hero without comment, and no condemnation of the prevalent code of morals is allowed to appear, unless by an occasional touch of irony. The portrait is drawn with such skill that the count, in spite of his biographer's candour, composes by his grand air on the reader much as he appears to have done on his contemporaries. The book is the most entertaining of contemporary memoirs, and in no other book is there a description so vivid, truthful, and graceful of the licentious court of Charles II. There are other and less flattering accounts of the count. His scandalous tongue knew no restraint, and he was a privileged person who was allowed to state even the most unpleasing truths to Louis XIV.
The Mémoirs de la vie du comte de Grammont contenant particulierement histoire amoureuse de la cour d'Angleterre sous la régne de Charles II were printed in the Netherlands with the inscription Cologne, 1713. Other editions followed in 1715 and 1716. Memoirs of the Life of Count de Grammont ... translated out of the French by Mr Abel Boyer was supplemented by a complete key in 1719. The Mémoires augmentés de notes et d'éclairissements was edited by Horace Walpole in 1772. In 1793 appeared in London an edition adorned with portraits engraved after originals in the royal college ii. An English edition by Sir Walter Scott was published by G. Bohn (1846), and this with additions was reprinted in 1889, 1896, etc. Among other modern editions are an excellent one: the Bibliothèque Charpentier edited by M. Gustave Brunet (1859); Mémoires (Paris 1888) with etchings by L. Boisson after C. Delort and an introduction by B. Gausseron; Memoirs 89), edited by. Mr H. Vizetelly; and Memoirs ... (1903), edited by Mr Gordon Goodwin.