In June 1792 his papers were seized at the foreign office, without anything incriminating being discovered; in July he was denounced, and after 10 August was proscribed. He took refuge in the house of a washerwoman, but was discovered, taken before the Legislative Assembly, and imprisoned in the Abbaye, where he perished in the September massacres. His relative, Louis Victor Henri, marquis de Montmorin de Saint Herem, head of the senior branch of the family, also perished in the massacre.