A good case to look at is the Dreyfus Affair.

A tl;dr of this case was that a young French Army officer was convicted of treason in 1894 and given life in prison for supposedly giving secrets to Germany. Alfred Dreyfus was Alsatian and Jewish, and was actually later re-tried and exonerated of the false charges in 1906 and later served in World War I.

Basically those involved in this egregious mistake fell into two groups: those that were heavy republicans and favored the French ideals of secularism (basically who cares if he's Jewish?) vs. the old guard in the military that tended lean more pro-Catholic with some anti-Semitic leanings.

There was also major press frenzy over the case, and I would argue that this was the French analogous event to the American "yellow journalism" fever before and during the Spanish-American War. A newspaper, La Libre Parole, basically used Dreyfus as a scapegoat for all French Jews, stating they weren't loyal to France because they were neither Catholic nor secular, both of which they saw as central to the French identity (you had to be one or the other).

But yeah things went insane during this case. It even got so crazy that Emil Zola actually wrote an open letter to French President Felix Faure titled "J'accuse....!" stating he and the government were anti-Semitic. Zola was eventually convicted of libel over the matter, but it goes to show how nuts this event was. It went back and forth between people that supported Dreyfus and were against him, and given the charged atmosphere following the failures in the Franco-Prussian War and how the region Dreyfus came from was eventually annexed by Germany, it nearly exploded into a much larger conflict in France. It was a powderkeg moment for sure. Also, there's so much info on this case it's nearly impossible to explain it in one comment. There was a crapload of moving parts and various viewpoints, factions, etc. It's an incredibly complex situation that's still debated in France today.

Sources:

Piers Paul Read, The Dreyfus Affair: The Scandal That Tore France in Two

Christopher Forth, The Dreyfus Affair and the Crisis of French Manhood This one is excellent in looking at the events from a gender perspective and how French ideas of masculinity played into the affair.

Tom Conner, The Dreyfus Affair and the Rise of the French Public Intellectual

While only a segment of your question, you may nevertheless be interested in this response I wrote which touches heavily on anti-semitism in France during the turn of the century.