The third child of Ioan Lahovary and Emma Lahovary, née Princess Emma Mavrocordat, Marthe spent her childhood on the Lahovary family's estates at Baloteşti and in the fashionable French sea resort Biarritz. On her first introduction into society, in 1900, she met Crown Prince Ferdinand, the Heir Apparent to the Romanian throne, but after a secret engagement of one year, Marthe married at 17 Prince George III Valentin Bibescu (Bibesco), scion of one of the country's prestigious aristocratic families. I stepped onto the European stage through the grand door, she wrote on her wedding day. Her father, who had been educated in France, held the post of minister of the Kingdom of Romania in Paris and, later, that of minister of foreign affairs of Romania.

Fluent in French at an early age (even before she could speak Romanian), Marthe spent the first years of her marriage under the tutelage of her mother - in - law, Princess Valentine Bibesco (née countess Riquet de Caraman - Chimay), who saw to it that the extensive education in European history and literature Marthe already had was reinforced. An old peasant woman, Baba Uţa [Outza], saw to it that she was also well versed in Romanian folk traditions and tales. Meanwhile, her husband, George, was chasing fast cars and other women, but adding to the family fortune at the same time.

Despite the birth of a daughter, Valentine, in 1903, despite her wide circle of friends, Marthe was bored. When George was sent by King Carol I on a diplomatic mission to the Mozzafar - al - Din Shah of Iran, in 1905, she eagerly embarked on the trip, recording her observations in a journal. Along the way, she stopped at Yalta, where she encountered the exiled Russian writer Maxim Gorki. It was in 1908, at the suggestion of Maurice Barrès, that Marthe completed her impressions of her Persian trip and published them. The French critics and writers were enthusiastic and amazingly complimentary. The travel memoirs she wrote about what she saw, Les Huit Paradis ("The Eight Paradises"), launched her on a lifelong career as a successful writer of both nonfiction and novels. She became the toast of Belle Epoque Paris, moving easily among the literary, aristocratic and political power elites. She was awarded the Prix de l'Academie Française and met Marcel Proust, who sent her a letter praising her book: You are not only a splendid writer, Princess, but a sculptor of words, a musician, a purveyor of scents, a poet.

Back in Bucharest, in 1908, Marthe was introduced to the German Kronprinz, Wilhelm. Wilhelm (who, despite Marthe's references to him as " the III", was never to succeed Wilhelm II) was married, but he nevertheless wrote warmly affectionate letters to Marthe for the following fifteen years. She and her husband were invited to Germany, in the autumn of the same year, as Wilhelm's personal guests, visiting Berlin, Potsdam, Weimar, and taking part in the Imperial regatta at Kiel. Marthe was awarded the supreme honor of accompanying Wilhelm in the imperial limousine, as it passed through the Brandenburg Gate, an entitlement otherwise reserved to members of the Imperial family. He would also try to involve Marthe in the international relations of pre-war Europe, secretly asking her to be the quiet mediator between France and Germany on the Alsace - Lorraine issue.

Among the European nobility, divorce was social death, but dalliance was definitely not. While Marthe and George continued in what was sometimes actually a mutually supportive partnership, they pursued their own interests. The French prince Charles - Louis de Beauvau - Craon fell in love with Marthe, an affair that lasted for a decade. In Paris, she also encountered the Roman Catholic Abbé Mugnier, who converted her from her Eastern Orthodox faith, and she began an extensive, frank correspondence with him that was to last 36 years.

Exhausted by so many sentimental disappointments, Marthe withdrew to Algeria, then part of the French colonial Empire, to stay with an aunt of her husband (Jeanne Bibesco), thinking about divorcing George and espousing the prince de Beauvau - Craon. Still, she felt she could not do it; George would prove to be surprisingly generous and understanding, giving her the Mogoşoaia Palace (Mogosoëa in certain French renderings) in 1912.

A couple of months before World War I, Marthe visited Spain, following the footsteps of Chateaubriand, her favorite French writer. In May, she was back in her country to greet Russian Emperor Nicholas II and his family, who were visiting the country after being invited by Princess Marie, wife of Prince Ferdinand.

In March 1915 Marthe met Christopher Thomson, the British military attaché, at a Palace soirée; he was arranging for Romania to join the Allies (although he did not agree with the policy, as Romania was unprepared for war). He remained devoted to her for the rest of his life. They corresponded regularly, and she dedicated four books to "C.B.T." Later he was a Labour peer, and Secretary of State for Air. She visited the site of his death in the R101 airship accident on December 1930 with their mutual friend the Abbé Mugnier.

When Romania at last entered the war on the Allied side in 1916, Marthe worked at a hospital in Bucharest until the German army burned down her home in Posada, in the Transylvanian Alps. She fled the country to join her mother and daughter in Geneva after a quarantine exile, imposed by the German occupants, in Austria - Hungary (as a guest of the princely family of Thurn and Taxis at Latchen). There she continued to write. For most of her life, she wrote every morning until lunchtime -- her journals alone fill 65 volumes.

In Switzerland, she began work on Isvor, pays des saules ("Isvor, Land of Willows"). It was Marthe's Romanian masterpiece, where she brilliantly conveyed the everyday life and customs of her people, the extraordinary mixture of superstition, deep philosophy, resignation and hope, and the unending struggle between age - old pagan beliefs and Christian faith.

Tragedy didn't spare Marthe, as her younger sister and her mother would commit suicide in 1918 and 1920 respectively.

For the Bibescos life after the war was more cosmopolitan than Romanian. Among her literary friends and acquaintances, Marthe counted Jean Cocteau, Paul Valéry, Rainer Maria Rilke, François Mauriac, Max Jacob, and Francis Jammes. In 1919, Marthe was invited to Prince Antoine Bibesco's wedding in London to Elizabeth Asquith, daughter of the former Prime Minister of the United Kingdom, Herbert Henry Asquith, later Earl of Oxford. Princess Elizabeth Bibesco, who died in Romania during World War II, is buried in the Bibesco family vault on the grounds of Mogoşoaia. Marthe for many years occupied an apartment in Prince Antoine's Quai Bourbon house at which she held literary and political salons.

During this postwar period she rebuilt Posada, her mountain home, and began restoring the other family estate, Mogoşoaia, the palace built in Byzantine style. Again in London, she met Winston Churchill in 1920, starting a warm friendship that would last until his death in 1965. When her daughter Valentine married the Romanian prince Dimitrie Ghika - Comăneşti (October 1925) in a dazzling traditional ceremony, three Queens attended, (Queen - mother Sophia of Greece, Princess Consort Aspasia Manos of Greece and Queen Marie of Yugoslavia).

Moving around Europe, acclaimed as each new book appeared -- Le Perroquet Vert (1923), Catherine - Paris (1927), Au bal avec Marcel Proust (1928) -- Marthe gravitated toward political power more than anything else. Without forgetting the former Kronprinz, Marthe had a short love affair with Alfonso XIII of Spain, and another with the French Socialist representative Henry de Jouvenel. In the latter case, the class differences shattered their relationship, something that Marthe used as the basis of her novel Égalité ("Equality", 1936). The Prime Minister of the United Kingdom, Ramsay MacDonald, found her fascinating. She visited him often in London and was his guest at Chequers. He wrote many touching, tender letters to her. Their close friendship ended only with his death.

Accompanying George, who was by then chasing fast planes - in addition to his numerous women - Marthe flew everywhere: the United Kingdom (she counted among her friends the Duke of Devonshire Edward Cavendish, the Duke of Sutherland George, Vita Sackville - West, Philip Sassoon, Enid Bagnold, Violet Trefusis, Lady Leslie and Rothschild family members), Belgium, Italy (where she met Benito Mussoliniin 1936), the Italian colony of Tripolitania (Libya), Istanbul, the United States (in 1934, as guests of Franklin D. Roosevelt and his wife Eleanor), Raguse, Belgrade and Athens.

Whatever she wrote was a critical success and also sold well. But the money wasn't enough to cover the heavy expenses of her Mogoşoaia project (where the pavement of the Grand Hall is covered with gold), so she began writing popular romances under the pseudonym Lucile Décaux, and articles for fashion magazines under her own name. She had a long term contract with The Saturday Evening Post and Paris - Soir. In the 1920s and the 1930s, Mogoşoaia Palace was to become the second League of Nations, as the French Minister of Foreign Affairs, Louis Barthou, put it. There, annually, Marthe hosted royalty (among others, Gustav V of Sweden and the Queen of Greece), aristocracy (princes Faucigny - Lucinge, Princes de Ligne, the Churchills, the Cahen d'Anvers), politicians and ministers, diplomats and writers (Paul Morand, Antoine de Saint - Exupéry).

As the winds of war began again to sweep across Europe, the princess began to prepare. She visited Germany in 1938 to see Wilhelm, and was introduced to Hermann Göring; she visited the United Kingdom in 1939 to meet George Bernard Shaw. Her older grandson, John - Nicholas Ghika - Comăneşti, was sent to school in England in the same year (he was not to see his homeland again for 56 years). Romania entered the war in 1941, this time on the losing side.

Prince George III Bibesco died on June 2, 1941; their relationship strengthened during his illness, even though he kept his mistresses. After visiting German - occupied Paris and Venice, she made a top secret visit to Turkey in 1943 together with her cousin, Prince Barbu II Ştirbey (Barbo Stirbey), trying to negotiate Romania's withdrawal from the Second World War. When the Red Army invaded her country, Marthe had a passport and connections enabling her to leave on September 7, 1945. Ironically it was not Marthe but her cousin Antoine Bibesco's wife Elizabeth who was the last Bibesco to be buried on the grounds of Mogosoaia after her death on April 7, 1945. Neither Marthe nor Antoine would ever return to Romania. When the communist government took power in 1948, it confiscated all Bibesco property. She settled in Paris.

Eventually, Valentine and her husband were released from Romanian detention in 1958, and allowed passage to Britain, where Marthe, now totally dependent on her writing for money, bought them a home, the Tullimaar residence at Perranarworthal in Cornwall. She remained in Paris, first living at the Ritz Hotel (1946 - 1948), then in her apartment at 45, Quai de Bourbon. In 1955, she was appointed a member of the Belgian Academy of French Language and Literature, on the seat previously held by Anna de Noailles (née Bibesco, princess Bassaraba de Brancovan). Marthe cherished the 1962 award of the Légion d'honneur. It was in 1960 that her novel (27 years in the making), La Nymphe Europe, which was really her autobiography, was published by Plon.

Now a grande dame, she enjoyed her last great friendship with a powerful leader, Charles de Gaulle, who invited her in 1963 to an Élysée Palace reception in the honour of the Swedish Sovereigns. De Gaulle also took a copy of Isvor, Pays des Saules with him when he visited Romania in 1968, and told her in the same year: ... you do personify Europe to me. Marthe was 82 years old.

In January 2001, a national poll of the most influential women in Romania's history placed princess Marthe Bibesco in the first position as the woman of the Millennium and of the 20th century.