French officer and diplomat who helped raise the princess Elizabeth to the throne of Russia.

La Chétardie entered French military service at an early age and rose through the ranks, becoming lieutenant (1721), major (1730), and colonel (1734). He performed well and received assignments to Holland and Prussia and in 1739 became ambassador to Russia. In order to secure a government more favourable to French interests, La Chétardie joined with the supporters of the youngest daughter of Peter the Great, Elizabeth, and, with the help of her French physician Jean-Hermann, Count de Lestocq, directed the maneuvering that placed her on the throne on Dec. 6, 1741. After Elizabeth's ascension La Chétardie received the imperial orders of St. Andrew and St. Anne and soon became an intimate of the new empress.

He departed from St. Petersburg in 1742 but returned there as ambassador in 1743. La Chétardie seems to have annoyed Elizabeth with his excessive attentions, however, and he was expelled from Russia in 1744. Returning to France in disgrace, he was briefly imprisoned in the citadel of Montpellier before reentering the French army in 1745. He then served in Italy until 1748, becoming a lieutenant-general in that year. In 1749 he became ambassador to the court of Turin, and he reentered military service when the Seven Years' War broke out in 1756.