By 1936, Le Creusot was the only French industrial site not to have experienced any work stoppages; in fact, during his 44-year reign over Schneider enterprises (1898–1942), Eugène II Schneider suffered only one major dispute at Le Creusot, in 1899. This situation reflects the systematic antiunion policy adopted by the ‘house’ union, which engaged in the defense of the company's interests and staged a lockout in July 1900. But how exactly did the creation of workers' representatives support the conversion of shop floors and eventually lead to the eviction of unions from Le Creusot? Our research is based on a singular case and historical facts but goes beyond this to reconstruct and interpret those facts using the yardstick of theory. We gathered multiple sources, including reports and correspondence among managers, news articles, accounts of workers' representatives, commentary by shop stewards and ordinary workers, managerial communication, union or professional tracts, minutes of meetings, and outcomes of elections. After presenting the case we investigated, we set out to demonstrate that the system of management participation, put in place in the Schneider enterprise, ultimately led to the weakening of the union movement within the company. Our case study reveals the strategic decisions made to derail the union system in Le Creusot, which modified industrial relations through the use of workers' representatives.