Wikipedia
"Résistancialisme" (literally, "Resistance-ism") is a neologism, created in 1987 by the French historian Henry Rousso, to describe the myth, particularly amongst Gaullists and Communists, which exaggerated the French involvement in the resistance to Nazi occupation during the Second World War. In particular, it was used to describe the belief that resistance was both unanimous and natural during the period, as well as the lack of historiographical interest in the role of French collaboration and the Vichy government.
It should not be confused with "Résistantialisme" (with a "t", literally "Resistant-ism"), a phrase coined by the Jean-Marie Desgranges, to criticize those who attempted to retrospectively fake or exaggerate their own involvement in the resistance for their own advantage, for instance François Mitterrand.