During the First World War some young Flemish intellectuals and writers took advantage of the German Flamenpolitik (the occupation politics in Flanders) in order to realise a number of socio-political, economic and linguistic goals in Flanders. The bourgeois and higher social classes, as well as the Belgian government, were only French speaking at that time. This agitation by Flemish artists and historians, politicians and writers is called activisme. Some of them strived for a Diets (a reunited Dutch-speaking) nation, based on a unifying idea of ‘Great-Netherland’ sentiments (Groot-Nederland). One of those ‘Diets’ writers was Wies Moens. His idea of a ‘Great-Dutch’ nation included not only the Netherlands and Flanders, but also the Afrikaans-speaking part of the South-African population. In the twenties Moens stood up for a cultural notion of the ‘Diets’ ideas, in the thirties and during the Second World War he gave it a more radical political-ideological significance. This paper focuses on the way young activists and Flemish nationalism at the end of the 19th century, and more particularly in the first decades of the 20th century, made use of the white Afrikaner nationalism, andmore specifically themystification of the (second) Anglo-Boer War, to enforce their own political message.