During the French Revolution, Haüy refused to take an oath accepting the Civil Constitution of the Clergy, and became a non-juring priest. He was thrown into prison after the monarchy was overthrown on August 10, 1792. Étienne Geoffroy Saint-Hilaire interceded on his behalf. Haüy was released just a few days before the September Massacres of September 2–7, 1792 in which many of the clergy were killed.