of the line to the Suisse Occidentale-Simplon, as under that arrangement there was the possibility of using its staff elsewhere during the annual winter service interruption. This management agreement was approved by the SOS's successor company, the Jura-Simplon-Bahn (JS) and retained finally also by the Swiss Federal Railways (SBB) until 1920. From the opening of the line onwards, passenger numbers continually increased, and after a short while were already significantly exceeding the predictions established at the time of the line's construction. Yet at the same time, the railway had to fight countless storms that again and again paralysed operations for days. The opening of the Gornergratbahn in 1898, the Simplon Tunnel in 1906 and the Lötschbergbahn in 1913 brought the Visp-Zermatt-Bahn further passengers. However, the upward trend met with an abrupt end at the outbreak of World War I. Foreign tourists stayed away from Switzerland, while coal prices massively increased. Passenger numbers fell back to the level of 1891. The timetable had to be substantially reduced, and fares strongly increased, but a cost covering operation was no longer possible. In the summer timetable for 1914, there were still six train pairs per day between Visp and Zermatt. After the outbreak of war there were only three, and from 1918 just two train pairs. In 1918, the total loss amounted to around 971,000 francs. After the war, passenger numbers initially increased again only slowly. In the midst of the emerging boom, a flood on 24 September 1920 destroyed about 300 metres of the formation between Visp and Ackersand. Even this event came after the Vispa had already been diverted during the winter of 1919/20 by avalanches and landslides onto the formation at Kin, causing serious damage. The resulting deficit, which to this day is the most recent in the history of the railway, gave the SBB a reason not to renew the expiring management contracts, and to return the management of the railway to the VZ from 1 January 1921. The railway's management was then allocated to a collective directorate also responsible for managing the Gornergratbahn. At the same time, in collaboration with Zermatt hoteliers, an office was set up to run the first international promotions for the Zermatt tourist resort. In 1927, passenger numbers once again reached pre war levels. In 1931, with 227,845 passengers, the line set a new record that was not surpassed until after World War II.