Soon afterward, he accompanied his uncle, François-Emmanuel Guignard, comte de Saint-Priest, the French ambassador to the Ottoman Empire, to Constantinople.

Initially a firm supporter of the French Revolution, d'Antraigues published a Mémoire sur les Etats Généraux ("Dissertation on the Estates-General") in 1788.

Horrified at the near death of Queen Marie Antoinette, whom it was rumored he had unsuccessfully tried to seduce years earlier, he suddenly changed his vision completely, becoming a defender of the Bourbon Monarchy.

He soon became part of a plot by the Marquis de Favras to help the royal family escape from the Tuileries Palace in Paris where they had been forced to move by the mob that had attacked Versailles.

The Venetian government later expelled Louis XVIII from its territory in 1796 as a direct result of threats from France, but d'Antraigues remained in Venice.

Travelling with the Russian ambassador to Venice and his entourage as they attempted to flee, d'Antraigues was arrested in Trieste by French troops, who then transported him and his family to Milan.

Soon after, Louis XVIII dismissed him as an agent because he feared that d'Antraigues had willingly betrayed the Pichegru negotiations and other Royalist secrets to Napoleon in exchange for his freedom.

In 1802, Czar Alexander I of Russia sent him as a Russian attaché to Dresden, the capital of the Kingdom of Saxony, but in 1806 he published a violent pamphlet against Napoleon and the French Empire, and was expelled by the Saxon government.

It was universally believed that d'Antraigues was the agent who revealed the secrets articles of the Treaty of Tilsit to the British cabinet, but his biographer, Leonce Pingaud, contests this.

[2] In England, he also became an intimate of fellow émigrés, Charles François Dumouriez and the duc d'Orléans (the future King Louis Philippe of the French).