In 1903, the workers at the railway companies went on strike, meaning they stopped working until their bosses met their demands. They felt their working conditions were very bad. They earned low wages for very hard work. The strike was successful. The bosses agreed to improve working conditions. When World War I began in 1914, the Netherlands stayed neutral. Train transportation was then used by armies. The railways were part of the war because it was easy to transport soldiers and equipment. The HSM and the SS had to work together very closely. In 1937, they merged, becoming the "Nederlandse Spoorwegen" or NS.