structural:reformatting, stylistic:style_transfer, stylistic:tone
Royal mistress

Through her position as court favourite, Pompadour wielded considerable power and influence. She was elevated on 12 October 1752 to duchess and in 1756 to lady-in-waiting to the Queen, the most noble rank possible for a woman at court. Pompadour effectively played the role of prime minister, becoming responsible for appointing advancements, favors and dismissals, and contributing in domestic and foreign politics.

In 1755, she was approached by Wenzel Anton, Prince of Kaunitz-Rietberg, a prominent Austrian diplomat, asking her to intervene in the negotiations which led to the Treaty of Versailles. This was the beginning of the Diplomatic Revolution, which saw France allied to their former enemy Austria.

Under these changed alliances, the European powers entered the Seven Years' War, which saw France, Austria and Russia pitted against Britain and Prussia. France suffered a defeat at the hands of the Prussians in the Battle of Rossbach in 1757, and eventually lost the American colonies to the British. After Rossbach, Madame de Pompadour is alleged to have comforted the king with the now famous: " au reste, après nous, le Déluge " ("Besides, after us, the Deluge "). France emerged from the war diminished and virtually bankrupt.

Madame de Pompadour persisted in her support of these policies, and when Cardinal de Bernis failed her, she brought Choiseul into office and supported and guided him in all his plans: the Pacte de Famille, the suppression of the Jesuits, and the Treaty of Paris (1763). Britain's victories in the war had allowed it to surpass France as the leading colonial power – something which was commonly blamed on Pompadour.

Pompadour protected the Physiocrates school (its leader was Quesnay, her own doctor) which paved the way for Adam Smith 's theories. She also defended the Encyclopédie, edited by Denis Diderot and Jean le Rond d'Alembert, against those, among them the Archbishop of Paris Christophe de Beaumont, who sought to have it suppressed. In Diderot's first novel, Les bijoux indiscrets (The Indiscreet Jewels), the characters of Mangogul and Mirzoza are allegories of Louis XV and Pompadour respectively. Diderot portrayed Pompadour in a flattering light, most likely to ensure her support for Encyclopedie. Pompadour had a copy of Les bijoux indiscrets in her library, which may explain why the crown did not pursue Diderot for such an indiscretion against the king.

The marquise had many enemies among the royal courtiers who felt it a disgrace that the king would thus compromise himself with a commoner. She was very sensitive to the unending libels called poissonnades, analogous to mazarinade against Cardinal Mazarin and a pun on her family name, Poisson, which means "fish" in French. Only with great reluctance did Louis take punitive action against her known enemies, such as Louis François Armand du Plessis, duc de Richelieu.