a nationwide railroad strike and a turning point for US labor law. Eugene Debs and the ARU called a massive boycott against all trains that carried a ______________ car. The federal government obtained an injunction against the union, Debs, and other boycott leaders, ordering them to stop interfering with trains that carried mail cars. After the strikers refused, President Grover Cleveland ordered in the Army to stop the strikers from obstructing the trains. Violence broke out in many cities, and the strike collapsed.