Then, at the end of July, the allied armies of Austria and Prussia, accompanied by a great many French noblemen, crossed the frontier and began their heralded invasion. The general in command, the Duke of Brunswick, issued a proclamation calling on the people of Paris to submit to their king, and threatening all sorts of dire things if they persisted in their rebellion. The proclamation acted like tinder to powder. The invasion united all parties for the moment. If the Duke of Brunswick succeeded, no man who had taken part in the Revolution could think his life or property secure, and France would return to the old feudal despotism, made worse by its dependence on foreign armies. The people of Paris and of France demanded immediate and vigorous action; the Assembly could not lead them, and the Jacobins seized their chance. Danton and his fellows addressed the crowds in the streets and told them that France would not be safe until the monarchy and the aristocracy had been exterminated. The people heard and believed, and by August first were ready to strike down any men their leaders pointed out to them. Danton and the Jacobins made their plans rapidly. They filled the floor and the galleries of the Assembly with men whose violent threats kept the deputies constantly in fear of physical force. They taught the people to hate all those who defended the constitution, and chief among the latter Lafayette, whom the Jacobins feared more than any other man in France. So great was their fury against him that Gouverneur Morris wrote to Jefferson at the beginning of August, “I verily believe that if M. de Lafayette were to appear just now in Paris unattended by his army, he would be torn in pieces.” On August tenth the mob, armed with pikes, surrounded the Tuileries. The King looked out on a crowd made up of the most vicious elements of the city. He tried to urge the National Guards to protect him, but they were demoralized by the shouts of the throngs. Finally he decided to take refuge with the National Assembly, and with the Queen and their children succeeded in reaching the Assembly chamber. The Swiss guards at the Tuileries attempted to make some resistance, but the mob drove them from their posts and killed many of them. The reign of terror spread. Nobles or citizens who had opposed the Jacobins were hunted out and murdered. When the Assembly adjourned the deputies found armed bands at the doors, waiting to kill all those who were known to have supported the constitution. Meantime the royal family had found the Assembly a poor refuge. A deputy had moved that the King be dethroned and a convention summoned to determine the future government of the country. The measure was instantly carried. Louis XVI. and his family were handed over to officers who took them to the Temple, which then became their prison.