With the rapid growth and consolidation of large railroad systems after 1870, union organizations sprang up, covering the entire nation. By 1901, 17 major railway brotherhoods were in operation; they generally worked amicably with management, which recognized their usefulness. Key unions included the Brotherhood of Locomotive Engineers , Brotherhood of Maintenance of Way Division , the Order of Railway Conductors, the Brotherhood of Locomotive Firemen, and the Brotherhood of Railroad Trainmen. Their main goal was building insurance and medical packages for their members, and negotiating bureaucratic work rules that favored their membership, such as seniority and grievance procedures. They were not members of the AFL, and fought off more radical rivals such as the Knights of Labor in the 1880s and the American Railroad Union in the 1890s. They consolidated their power in 1916, after threatening a national strike, by securing the Adamson Act, a federal law that provided 10 hours pay for an eight-hour day. At the end of World War I they promoted nationalization of the railroads, and conducted a national strike in 1919. Both programs failed, and the brotherhoods were largely stagnant in the 1920s. They generally were independent politically, but supported the third party campaign of Robert M. La Follette Sr. in 1924.
Question: Who went on strike after WWI?
Answer: unions