In the history of France, the First Republic (Première République), sometimes referred to in historiography as Revolutionary France, and officially the French Republic (République française), was founded on 21 September 1792 during the French Revolution. The First Republic lasted until the declaration of the First Empire on 18 May 1804 under Napoléon Bonaparte, although the form of the government changed several times. This period was characterized by the downfall and abolition of the French monarchy, the establishment of the National Convention and the Reign of Terror, the Thermidorian Reaction and the founding of the Directory, and, finally, the creation of the Consulate and Napoleon's rise to power. Proclamation of the abolition of the monarchy Under the Legislative Assembly, which was in power before the proclamation of the First Republic, France was engaged in war with Prussia and Austria. In July 1792, the Duke of Brunswick, commanding general of the Austro–Prussian Army, issued his Brunswick Manifesto, threatening the destruction of Paris should any harm come to King Louis XVI of France. This foreign threat exacerbated France's political turmoil amid the French Revolution and deepened the passion and sense of urgency among the various factions. In the insurrection of 10 August 1792, citizens rioted the Tuileries Palace, killing six hundred of the King's Swiss guards and insisting on the removal of the king. A renewed fear of anti-revolutionary action prompted further violence, and in the first week of September 1792, mobs of Parisians broke into the city's prisons. They killed over half of the prisoners, including nobles, clergymen, and political prisoners, but also common criminals, such as prostitutes and petty thieves. Many victims were murdered in their cells: raped, stabbed, and/or slashed to death. This became known as the September Massacres. National Convention As a result of the spike in public violence and the political instability of the constitutional monarchy, a party of six members of France's Legislative Assembly was assigned the task of overseeing elections.