The Vlaams Nationaal Verbond (VNV) (Flemish National Alliance) was a Flemish pro-Nazi party founded in 1933 by 'den leider' Staf de Clercq as a radical version of the Frontpartij (Front Party). Their program was based on radical Flemish nationalism, uniting all Flemish parties and, originally, independence. However, their program soon dropped real independence as a meaninful goal as they embraced the vision of the "Greater Netherlands" (Dietsland) which was an advocated union of Belgian and French Flanders with the Netherlands. Although the party had support from some Flemish Catholics the Church leadership opposed it because of this vision which was anti-Belgium as (back then at least) the clergy was very much monarchist and loyal to the Catholic Royal Family and did not want Flemish Catholics put under the Protestant Dutch monarchy. Of course, in the end, the Nazi invasion would mean there was no Dutch monarchy anyway as the Netherlands became an occupied state with a Nazi government.
Most of the support for the VNV came from the middle class, lower middle class and the agricultural community, because of all of this groups had suffered the most in the economic crisis and were the most likely to fall victim to their utopian propaganda. The VNV grew the most during the 1930's because of this reason. At first they were not totally un-democratic (trusting they could win a democratic majority of the Flemish population) but later they adopted more of the styles of the Nazis and the NSB the Dutch Nazis and became more authoritarian. Staf de Clercq said that if the Germans invaded Belgium he would not collaborate with them but when the event came he immiediately collaborated. However, de Clercq was disappointed in his hope of becoming a little dictator when Hitler did not work with any civilian government but simply put Belgium under the military rule of General Alexander von Falkenhausen. Further, Hitler chose different leaders to oversee the formation of the Flemish-SS which undercut support for the VNV.
Flemish volunteers for the SS were organized into combat units and de Clercq died in 1942. His successor, Hendrik Elias, tried to deal with the Nazis to accomplish the goals of the VNV but he had no more success. The Nazis would have no "Greater Netherlands" considering the Dutch and Flemish to be their Germanic cousins who should be included in their own "Greater Germany" Third Reich. Annexation was finally ordered in 1944 but only 7 weeks later, thankfully, the Allies ended the Nazi occupation of Belgium. Elias fled to Germany, was arrested by the Allies, sent back to Belgium, sentanced to death as a traitor but then downgraded to life in prison but even then managed to convince the court to reduce his sentance and he was later released to write his autobiography. He died in 1973. What is most disturbing about the VNV (as for example compared to the Rexists) is that there are still some who support their views, even by use of violent means, to attack non-Flemish and cling to the "Greater Netherlands" vision.