[5] A strong admirer of Benito Mussolini, but equally demonstrating a staunch hatred of Germany, Hoornaert was a member of the far right veterans' group National Legion (French: Légion Nationale, Dutch: Nationaal Legioen) which was established in Liège in 1922.

[3] As Legion leader Hoornaert participated in the 1934 Montreux Fascist conference, campaigned in support of the Italian invasion of Ethiopia (1935–37) and raised volunteers for the Nationalists in the Spanish Civil War (1936–39).

[6] He has been compared to Georges Valois in leading a pioneer fascist movement that rejected Nazism and instead took its impetus from the likes of Charles Maurras whilst drawing on disaffected ex-servicemen for its membership.

[5] As well as leading the Legion Hoornaert was also briefly involved with the National Corporate Workers' Union (Nationaal Corporatief Arbeidsverbond, or NACO), a group set up by industrialist Charles Somville in June 1933.

As a consequence he joined the Légion Belge, a far right resistance movement led by dissident Rexists who opposed the occupation of Belgium.