Peter Lefev was Müllenbach's mayor, and in 1899, it was Peter Schmitz. Another census in 1900 revealed that 932 people lived in Müllenbach, among whom were 200 children attending primary school. In 1901, there was a new parish priest, Franz Kirchesch, born in Wissen; he served until 1912. In 1903, Bartholomäus Schmitz was Müllenbach's mayor. Another census held in 1905 found that the village's population was “half male, half female”. It is unclear how this could be said when the total population figure was 905 – an odd number. Also in 1905, oil lamps were replaced with carbide lamps in the slate mines. They gave off a brighter light and were held to be more conducive to miners’ health. Another innovation came to the mines in 1908. The Müllenbacher Dachschieferwerk began using a diesel-powered railway to haul slates. Another railway with cable-hauled slate cars was also built. This same year, Peter Schmitz was Müllenbach's mayor once again. The 2 December 1910 census put the number of villagers at 946. In 1911, there was a murder in Müllenbach: on the night of 2 to 3 February, a boy named Anton Lehnen, from Müllenbach, was done to death by five lads, also from Müllenbach. They were all found guilty in court in Koblenz on 3 May. One was released early, and the three ringleaders, Peter Krämer I, Reuter and Lefev, were, owing to mitigating circumstances, sentenced to prison terms ranging from 9 to 10 years. Peter Krämer II got half a year in jail. The newspaper reported the crime, expressing revulsion at the murderers’ bestiality. In 1912, Müllenbach's parish priest was Cornelius Mehren, born in Damscheid, who held the post until 1921. First World War On 1 August 1914, war broke out between Germany and Austria-Hungary on the one side, and Russia, France and Serbia on the other. On Friday 31 July, towards 5 o’clock in the morning, a rider had come from Kaisersesch, bringing the news of the declaration of war. In 1915, Stephan Valerius was Müllenbach's mayor, and his deputy was Mathias Josef Gilles. Later that same year, though, the deputy took over the mayor's office, and his deputy was Mr. Scheider. Amid the general fear that the Great War would last longer than first expected, older youth were being readied for military service. The parochial company numbered 75 men, each of whom received a soldier's cap. Because wages were