How was Vichy France remembered by the country after World War II? That is, how did the French public as well as French government interpret their involvement in World War II; how did they teach it?

This is a complicated question, in part because the French public and the French government are two different beasts. Also, the situation evolved a lot over the decades.

The official governmental stance immediately following the war was, to sum it up, that "Vichy wasn't France". During the war, after the Appeal of 18 June (1940), De Gaulle established himself as the head of a government-in-exile named "Free France", and that idea was perpetuated after the Liberation, by the ordinance of 9 August 1944, stating that the legitimacy of the Vichy regime was, I quote, "null and void".

This is also when the national myth took roots for a while that "most French people were resistants", at least to a point or after a fashion, even if they didn't all took arms. There were large purges at the Liberation against past collaborators, for sure, but the dominant worry seemed to be if those purges weren't, you know, too harsh. (I mean, there were cases of excessive, popular violence, but not to the point of the "black legend" of the so-called "wild purge", with fanciful figures circulating back then, pretending more than 100 000 people were lynched. The more recent historiography, like François Rouquet and Fabrice Virgili's Les Françaises, Les Français et l'Epuration [2018], points out that this discourse was actually mainly a way to target communists.)

That idea of a "mostly resistant France" was also the one largely sold by the French movie industry for decades, with tonally serious movies like René Clément's La Bataille du rail (The Battle of the Rails, 1946), Le Père tranquille (Mr. Orchid, 1946) and later Paris brûle-t-il? (Is Paris burning?, 1966) as well as Jean-Pierre Melville's L'Armée des ombres (Army of Shadows, 1969), to name a few, or even comedic movies, most notably Gérard Oury's La Grande Vadrouille ("The Great Stroll", 1966), which remained the most successful movie of the history of French box-office until Titanic. Claude Autant-Lara's La Traversée de Paris ("The Trip across Paris", 1956), another comedy, was an oddity for its rare choice to show a less stellar aspect of the times, focusing on black market.

During that same era, Robert Aron's Histoire de Vichy ("History of Vichy", 1954) was largely accepted as the reference book on the Vichy regime, substantiating the (actually revisionist) "sword and shield thesis", meaning De Gaulle was the "sword" fighting the nazis but Petain was the "shield" protecting the French people from them and collaborating as little as possible with the Germans.

De Gaulle's death in 1970, however, proved to be a turning point, opening gates for a less heroic narrative. 1971 documentary Le Chagrin et la pitié (The Sorrow and the Pity), by Marcel Ophuls, depicted a French population during Occupation made of only very few resistants, very few collaborators, some profiteers, and a vast majority of people in a "wait-and-see" attitude. 1973 saw the French translation of Robert Paxton's historical essay Vichy France (originally published in '72 in USA), which completely challenged Robert Aron's version of History, and proved that the Vichy regime, not only did not minimize its collaboration, but went actually out of its way, most notably when it came to round up and deport Jews to the nazi concentration camps. Both the documentary and the essay generated heated debates in the public opinion, as did Louis Malle's movie Lacombe Lucien in 1974, focusing on a young, coarse French peasant becoming a collaborator during the last months of the war.

In 1978, L'Express magazine published an interview of Louis Darquier, former "Commissioner-General for Jewish Affairs" under the Vichy regime, who fled to Spain after the Liberation. Among other things, the man allegated that Auschwitz gas chambers were used "only to gas lice". The interview was met with an immense backlash, creating a scandal that put the spotlight on two things. First, the fate of Jews under the Vichy regime, an aspect of things that until then was relatively sidelined in the general representations of that era. And second, the not only remaining, but growing, presence of negationist people, most notably the French academic and Holocaust-denier Robert Faurisson, who applauded to Darquier's interview.

It is also worth noting that this is the same year that Maurice Papon became Minister of Finance. Papon was already an official during the Vichy regime and nonetheless continued his career afterwards, most notably becoming préfet de police (Chief of Police) of Paris from 1958 to 1967, where he was responsible for bloody repression during the Algerian War (Paris massacre of 1961 and Charonne Station massacre of 1962). His past finally caught up to him in 1981 when it was discovered and exposed by the newspaper Le Canard enchaîné, leading to the start of a long and highly mediatic trial under the accusation of crime against humanity.

Meanwhile, the "Vichy wasn't France" stance kept being the official position of every French government of the 5th Republic. Elected in 1981, Socialist president François Mitterand stayed in line, about this, with his predecessors from the right, De Gaulle, Pompidou and Giscard d'Estaing.

But the question of the fate of Jewish people under the Vichy Regime became more and more pregnant following the publication, that same year, of Robert Paxton (again) and Michael Marrus' Vichy et les Juifs (Vichy and the Jews), a violent denounciation (Paxton would later recognize himself that he was at first a bit too harsh). More particularly, the public opinion's on this started to cristalise around a particular, symbolic event: the "Vel' d'Hiv' Roundup", a mass arrest of 13000 foreign Jewish families by the French police.

In 1992, for the 50 years commemoration of the round up, François Mitterand made a first symbolic step by being the first French president to show up and lay flowers, but he didn't speak there, and he kept repeating in interviews the same official position, saying "Don't demand accounts to the Republic, [...] the 'French State' [i.e. Vichy regime] wasn't the Republic" that same year, or, in 1994, "I will not apologize in the name of France. The Republic has nothing to do with it. I do not believe France is responsible."

However, in 1995, his successor, Jacques Chirac, finally reversed this position, stating in a public speech for the 53th commemoration of the Round Up: "These black hours will stain our history forever and are an injury to our past and our traditions. [...] France, home of the Enlightenment and the Rights of Man, land of welcome and asylum, France commited on that day the irreparable." And in 1998, Maurice Papon was eventually given a ten-year-sentence as complicit in crimes against humanity for having organized eight "death trains". (Aged 88 at the time, he would only serve three years due to his old age and medical problems.) The two events were catalyst for a large reckoning in the broad public about France's involvement of the World War II.

I won't develop much further due to the "20 years rules" of the subreddit, but I believe it is worth noting quickly that every French president since then, regardless of political orientation, has kept in line with Jacques Chirac's position; yet also that, nonetheless, both the "Vichy wasn't France" stance and, even, the "shield thesis" (in particular the idea that Vichy actually protected French Jews) are still parts of the Far Right's speeches.