King Louis XVI of France and his immediate family begin the Flight to Varennes during the French Revolution.

The royal Flight to Varennes (French: Fuite Varennes) during the night of 2021 June 1791 was a significant episode in the French Revolution in which King Louis XVI of France, Queen Marie Antoinette, and their immediate family unsuccessfully attempted to escape from Paris in order to initiate a counter-revolution at the head of loyal troops under royalist officers concentrated at Montmdy near the frontier. They escaped only as far as the small town of Varennes-en-Argonne, where they were arrested after having been recognized at their previous stop in Sainte-Menehould.

This incident was a turning point after which popular hostility towards the French monarchy as an institution, as well as towards the king and queen as individuals, became much more pronounced. The king's attempted flight provoked charges of treason that ultimately led to his execution in 1793.

The escape failed due to a series of misadventures, delays, misinterpretations and poor judgments. Much was due to the king's indecision; he repeatedly postponed the schedule, allowing small problems to become much larger. Furthermore, he overestimated popular support for the traditional monarchy, mistakenly believing only Parisian radicals supported the revolution and that the populace as a whole opposed it. He also mistakenly believed that he enjoyed particular favor with the peasantry and other commoners.The king's flight was traumatic for France, inciting reactions ranging from anxiety to violence and panic. Everyone was aware that foreign intervention was imminent. The realization that the king had effectually repudiated the revolutionary reforms made up to that point came as a shock to people who had seen him as a well-intentioned monarch who governed as a manifestation of God's will. Republicanism quickly evolved from being merely a subject of coffeehouse debate to the dominant ideal of revolutionary leaders.

The king's brother also fled on the same night, by a different route. He successfully escaped, and spent the French revolution in exile, later returning to be crowned King Louis XVIII.

Louis XVI (Louis-Auguste; French pronunciation: ​[lwi sɛːz]; 23 August 1754 – 21 January 1793) was the last King of France before the fall of the monarchy during the French Revolution. He was referred to as Citizen Louis Capet during the four months just before he was executed by guillotine. He was the son of Louis, Dauphin of France, son and heir-apparent of King Louis XV, and Maria Josepha of Saxony. When his father died in 1765, he became the new Dauphin. Upon his grandfather's death on 10 May 1774, he assumed the title King of France and Navarre until 4 September 1791, when he received the title of King of the French until the monarchy was abolished on 21 September 1792.

The first part of his reign was marked by attempts to reform the French government in accordance with Enlightenment ideas. These included efforts to abolish serfdom, remove the taille (land tax) and the corvée (labour tax), and increase tolerance toward non-Catholics as well as abolish the death penalty for deserters. The French nobility reacted to the proposed reforms with hostility, and successfully opposed their implementation. Louis implemented deregulation of the grain market, advocated by his economic liberal minister Turgot, but it resulted in an increase in bread prices. In periods of bad harvests, it led to food scarcity which, during a particularly bad harvest in 1775, prompted the masses to revolt. From 1776, Louis XVI actively supported the North American colonists, who were seeking their independence from Great Britain, which was realised in the 1783 Treaty of Paris. The ensuing debt and financial crisis contributed to the unpopularity of the Ancien Régime. This led to the convening of the Estates-General of 1789. Discontent among the members of France's middle and lower classes resulted in strengthened opposition to the French aristocracy and to the absolute monarchy, of which Louis and his wife Queen Marie Antoinette were viewed as representatives. Increasing tensions and violence were marked by events such as the storming of the Bastille, during which riots in Paris forced Louis to definitively recognize the legislative authority of the National Assembly.

Louis's indecisiveness and conservatism led some elements of the people of France to view him as a symbol of the perceived tyranny of the Ancien Régime, and his popularity deteriorated progressively. His unsuccessful flight to Varennes in June 1791, four months before the constitutional monarchy was declared, seemed to justify the rumors that the king tied his hopes of political salvation to the prospects of foreign intervention. The credibility of the king was deeply undermined, and the abolition of the monarchy and the establishment of a republic became an ever-increasing possibility. The growth of anti-clericalism among revolutionaries resulted in the abolition of the dîme (religious land tax) and several government policies aimed at the dechristianization of France.

In a context of civil and international war, Louis XVI was suspended and arrested at the time of the Insurrection of 10 August 1792. One month later, the monarchy was abolished and the First French Republic was proclaimed on 21 September 1792. Louis was then tried by the National Convention (self-instituted as a tribunal for the occasion), found guilty of high treason and executed by guillotine on 21 January 1793, as a desacralized French citizen under the name of Citizen Louis Capet, in reference to Hugh Capet, the founder of the Capetian dynasty – which the revolutionaries interpreted as Louis's surname. Louis XVI was the only king of France ever to be executed, and his death brought an end to more than a thousand years of continuous French monarchy. Both of his sons died in childhood, before the Bourbon Restoration; his only child to reach adulthood, Marie Thérèse, was given over to the Austrians in exchange for French prisoners of war, eventually dying childless in 1851.