In September 1939, Colin, along with Robert Poulet, Pierre Daye and ten other journalists (most of them fascists, but including some left-wing pacifists) signed a pro-German manifesto calling for Belgian neutrality in the war.
One of Colin's associates, Robert Poulet, had in the meantime secretly met King Leopold III's private secretary, Count Capelle, and obtained a tentative royal approval for the project.
However, as the war dragged on, German victory became less certain and food rations decreased, more and more Belgians joined the ranks of those who criticized the "New Order".
In 1943, various members of the Belgian Resistance, led by Marcel Demonceau, hatched the plan to kill both Colin and the Rexist leader Léon Degrelle.
The attempt on the life of Degrelle failed because Demonceau was arrested at his hiding-place in Ixelles together with many associates, British airmen and members of the Belgian London-based Intelligence Service.