As in the case of many revolutions, the first is followed by a second. (The first government of the U.S. for instance, the Articles of Confederation, was soon replaced as ineffective.) In France, the first revolution created a Constitutional Monarchy which Louis XVI was forced to accept. The National Assembly had erred, however, in providing that none of its members would be eligible for election to the new Legislative Assembly. Those elected to the new assembly, many of whom were known as Jacobins by reason of their membership in a local political club, were younger and tended to be more radical. They distrusted monarchy in any form, and wanted a liberal revolution. They were prone to bombastic speeches and high sounding oratory during which, among other things, they grouped "despotic monarchs" and "useless aristocrats" together.
The Assembly declared war on Austria due to a perceived threat that Francis II would attempt to restore the French Monarchy. When things went poorly during the war, a radical mob whipped up in patriotic frenzy accused Louis XVIand Marie Antoinette (who was Austrian) of treason. They were arrested, imprisoned, and the first Republic of France proclaimed.