Assembling armies to fight a war. During the period of classic European wars (when there was a formal declaration of war - roughly, the period from the 1850s to 1945) the huge armies of conscripts had to be summoned to their barracks, put on trains and sent to the borders in an elaborate plan, such as that devised by Von Schlieffen for the First World War. It was the main task of the General Staff to plan how to do this. In an era without computers this was a huge task. It usually involved the use of the rail network, horses and route marches.

It is often claimed that the First World War took the form it did because each power had only one plan, and there was no means of improvising any variation because it required the coordination of the whole railway system, each part of which had to harmonise with the rest.