From the series "Handbuch der Verbände und Truppen des deutschen Heeres 1914-1918". The importance of railways for the transport of mass armies had been recognised by the army command at an early stage. Accordingly, the General Staff had drawn up clear plans for the use of railways in the event of war. The actual importance of the railways in the war, however, exceeded all expectations: Not only did lines have to be restored and operated in the conquered territories, but all troop and supply transports had to be handled by rail under difficult conditions. With the widespread expansion of the theatres of war, the extensive railway network demanded a constantly growing staff. In spring 1918, the railway network in operation covered about 20,000 km, while the personnel of the railway troops had grown to almost 180,000 men. All command posts, railway authorities and troops are covered in detail for the first time in this volume, providing an in-depth picture of the complex organisation of the field railway system in the First World War.