Declaration of Pillnitz
The Declaration of Pillnitz was a statement of five sentences issued on 27 August 1791 at Pillnitz Castle near Dresden by Frederick William II of Prussia and the Habsburg Leopold II, Holy Roman Emperor who was Marie Antoinette's brother. It declared the joint support of the Holy Roman Empire and of Prussia for King Louis XVI of France against the French Revolution.
Background
Since the French Revolution of 1789, Leopold had become increasingly concerned about the safety of his sister Marie Antoinette and her family, but felt that any intervention in French affairs would only increase their danger. At the same time, many French aristocrats were fleeing France and taking up residence in neighbouring countries, spreading fear of the Revolution and agitating for foreign support to Louis XVI. After Louis and his family had fled Paris in the hopes of inciting a counter-revolution, known as the Flight to Varennes in June 1791, Louis had been apprehended and was returned to Paris and kept under armed guard. On 6 July 1791, Leopold issued the Padua Circular, calling on the sovereigns of Europe to join him in demanding Louis' freedom.Purpose
Calling on European powers to intervene if Louis was threatened, the declaration was intended to serve as a warning to the French revolutionaries to stop infringing on the king's prerogatives and to permit his resumption of power.The declaration stated that Austria would go to war if and only if all the other major European powers also went to war with France. Leopold chose this wording so that he would not be forced to go to war. The addition of 'all' also masked how many powers were expected to be involved before Austria got involved. He knew that the British prime minister, William Pitt, did not support war with France. Leopold issued the declaration only to satisfy the French émigrés who had taken refuge in his country and were calling for foreign interference in their homeland.