The French Revolution destroyed the ties between the two states, despite appeals by the French National Assembly for Austria to honour the Treaty of 1756. In 1792, the Austrians sent troops to invade France, threatening to destroy Paris unless Louis XVI, now reduced to a constitutional monarch, was restored to his previous status. The Austrians suffered a defeat at the Battle of Valmy and Louis XVI was overthrown and, together with Marie Antoinette, executed the following year. Austria now joined a coalition of states trying to crush the French revolutionaries by force, and Vienna became one of the centres of anti-revolutionary activity by giving shelter to many French royalist refugees.