Louise Elisabeth de Lamoignon was born on October 6, 1763 at Paris to the noble Lamoignon family. Married in 1779 to Louis Le Peletier de Molé, she suffered the French Revolution destruction of her family — most of her family being guillotined during the Reign of Terror (1793–1794).
During the Revolution, Louise Elisabeth survived by fleeing into hiding at Vannes. After the Revolution, she undertook the vocation of the post-Revolutionary Catholic reconstruction.
In 1803, at the age of 40, Louise Elisabeth founded the Sisters of Charity of Saint-Louis at Vannes — dedicated to the education of French Catholic girls in the post-Revolutionary period. She served as Superior of the Sisters until her death in 1825.