A decision to remove the Battle of Verdun, the longest of the First World War, from the French national school curriculum, has provoked outrage among conservative politicians.

Verdun was fought on the Western Front between the French and German armies, with 700,00 soldiers killed or injured. But the education ministry has decided that it is more valuable for French schoolchildren to focus on the Battle of the Somme because of its international dimension. It was fought by armies of the British Empire, allied with the French, against the Germans, with more than a million soldiers killed or injured.

Conservative MPs voiced indignation that the latest issue of the education ministry’s official gazette has dropped Verdun from the battles listed as forming part of the curriculum for the next school year.

Jean Rottner, the centre-Right president of the Grand Est region which includes Verdun, in north-eastern France, tweeted: “Doing away with teaching the Battle of Verdun [is] an error.”

He posted a 1984 photograph of François Mitterrand, then the French president, holding hands with Helmut Kohl, the former German chancellor, at a commemoration in Verdun. The Battle of Verdun, he argued, “is not simply a historical event, it is a subject of historical importance that symbolises both the rifts between France and Germany and the reconciliation of our two nations.”