 Complete the following phrase:  The Gäubahn StuttgartTuttlingenImmendingen was primarily of regional importance at this time. The terminus of all long-distance travel was Immendingen. However, by the end of the 19th century trip times were becoming quite a bit shorter, to the point where the trip between Tuttlingen and Stuttgart had been cut down to only 3 hours in 1897, 4 to 5 hours less than in the 1870s. Starting in 1900, 3 daily express long-distance trains traversed the line, some of the time from Stuttgart via Immendingen all the way to Zurich. This trip did still require that passengers change trains in Immendingen. Around the turn of the century, the Royal Württemberg State Railways mostly used the steam locomotives of the class Württemberg AD for their express service, which were in turn replaced by the class Württemberg C during World War I. The class Württemberg T 5 was used for regional service. The 9th of April 1917 saw what was probably the most famous passenger on this line, when the leader of the 