After the First World War, the Cologne–Aachen railway was located in the French occupation zone. France intended to transport raw materials via this line from the Ruhr, which was also occupied, but the German railway workers refused to work with them as passive resistance. During the occupation, the line was blocked to regular traffic several times so that French crews could operate coal trains from the Ruhr to France without having to observe German signalling and rail regulations. Occasional acts of sabotage to prevent these operations were mostly unsuccessful. The line was returned to German control with the end of the occupation of the Rhineland.