The defense of nascent trade unionism in late-nineteenth-century America is a bright chapter in the history of the Catholic Church in the United States. When a nervous Vatican was prepared to write off trade unions as the kind of “secret societies” the Church had long opposed, Cardinal James Gibbons of Baltimore defended the Knights of Labor in Rome and forestalled a Vatican condemnation of American unions—an accomplishment that helped the Church retain the loyalty of working class people.
Gibbons’s defense of the Knights of Labor may or may not have had much influence on Pope Leo XIII’s endorsement of labor-organizing in the 1891 encyclical Rerum Novarum, but it set a pattern of Catholic support for trade unionism that continued in the United States for a century. That support seemed vindicated anew when the “independent self-governing trade union” Solidarity played a crucial role in the collapse of European communism in the 1980s.