It was the world’s first experience of antisemitism “gone viral”, said Barbara Warnock, a co-director of the oldest Holocaust archive, the Wiener Holocaust Library in London .

It was 1894 and printing presses were faster than ever before. France’s prohibitive censorship laws had been lifted, and then along came the Dreyfus affair: a public shouting match that followed the wrongful conviction for treason of Alfred Dreyfus, a 36-year-old French army captain.

The clash between those insistent on Dreyfus’s guilt, as a Jewish man deemed to have a questionable allegiance to the French republic, and his outraged defenders triggered a deluge of newspaper specials, bespoke journals, posters and other polemics.

Alfred Dreyfus, who was exonerated 120 years ago.…