A question about Napoleon Bonaparte’s return to power

Yes, Napoleon had been replaced in 1814 as head of the French state by a king, Louis XVIII, the younger brother of the guillotined King Louis XVI from the house of Bourbon. Louis essentially took over the Napoleonic state intact, including command of Napoleon's remaining army, and oversight of many bureaucrats appointed by Napoleon. Almost all of Napoleon's marshals remained in the French military, swearing oaths to the new Bourbon king.

Some of this changed during Louis's 10 months in power during the First Restoration — the army was significantly reduced in size, for one, and a new royal bodyguard, the "maison militaire" or Military Household, was created out of die-hard emigre nobles. In fact these actions helped weaken Louis's hold on the throne and enable Napoleon's return — they weren't thorough enough to purge lingering Napoleonic supporters, but were disruptive enough to create lots of resentment among soldiers, especially officers, who were fired from their job in the army as a bunch of puffed-up nobles with little to know military experience were put on the payroll.

All this meant that when Napoleon escaped from Elba, the civil officials confronting him and the soldiers sent to stop him were by and large relics of his former regime. It's no surprise that many of them, especially the soldiers, switched sides from Louis to Napoleon the first chance they got.

This shouldn't overstate Napoleon's control. Large parts of France remained cool to the emperor's return or even launched pro-Bourbon rebellions (these did little of consequence except suck away soldiers that Napoleon could have badly used at Waterloo). When he landed in Provence, he imperiously expected local towns there to immediately join him, and was surprised and put off when gates were shut in his face and his scouts arrested. This was an area that had suffered badly under the Napoleonic Wars, chiefly by British blockades cutting off trade out of Marseille and other ports, and they were firmly on the side of the Bourbons and peace versus Napoleon and renewed war. It wasn't until Napoleon traveled north into the more Bonapartist area around Grenoble that towns and soldiers began turning their coat.

The most dramatic switch was that of Marshal Michel Ney, who had served under Napoleon for a decade, including a valiant and much-praised action commanding the rear guard during the devastating retreat from Moscow. Ney famously swore to Louis that he would bring Napoleon back "in an iron cage," but when his detachment of troops met Napoleon, Ney switched sides instead. Historians still debate the degree to which this was premeditated and the degree to which Ney was swept along by events (and the determination of many of his soldiers to switch sides whatever he did), but in either case, Ney ended up in front of a firing squad for his treason when the Bourbons were restored again post-Waterloo.

After a few weeks of this, Napoleon finally reached Paris, at the head of an increasingly large army and with a seemingly unstoppable tide of momentum. Louis and other officials lost their nerve and fled, the glorified maison militaire having proved useless at anything other than ticking off the real army. The headline from the official government newspaper, the Moniteur, sums it up best: "The king and the princes left in the night. H.M. the Emperor arrived this evening at eight o’clock in his palace of the Tuileries at the head of the same troops which had been sent to block his route this morning."

When the Bourbons were restored for a second time after Waterloo, they took a very different approach: a thoroughgoing purge in which vast swathes of the army and civil service were sacked, and some offenders brought up on charges of treason and other crimes. Ney was merely the most famous victim of this "Legal White Terror"; so named because it was compared to the Revolution's Reign of Terror, but by royalists (whose color was white), and because it was conducted by force of law as opposed to the illegal White Terror of vigilante justice that hard-core ultra-royalists perpetrated in some areas of the country. The alliance of foreign powers who had beaten Napoleon at Waterloo also made sure to exile him much further from France than Elba, to the infamous St. Helena, and they retained an army of occupation on French soil for several years to put down any other Bonapartist (or republican) uprisings.

Sources

Austin, Paul Britten. 1815: The Return of Napoleon. Barnsley: Frontline Books, 2002.
De Bertier de Sauvigny, Guillaume. The Bourbon Restoration. Translated by Lynn M. Case. Philadelphia: The University of Pennsylvania Press, 1966.
Haynes, Christine. Our Friends the Enemies: The Occupation of France After Napoleon. Cambridge, Mass., and London, England: Harvard University Press, 2018.
Jardin, André, and André-Jean Tudesq. Restoration & Reaction, 1815-1848. Translated by Elborg Forster. Cambridge: Cambridge University Press, 1983.
Mansel, Philip. Louis XVIII. Rev. ed. Phoenix Mill: Sutton, 1999.
My podcast, The Siècle, about France 1814-1914