When the Vennbahn was built, the railway was in German territory. However, due to the Treaty of Versailles in 1919, Belgium gained parts of German territory, including Eupen, Malmedy and Sankt Vith. 

Parts of the railway also came into Belgian hands, such as the 1-kilometre stretch near the German town of Hemmeres, a borough of Winterspelt. The signalman's house also became Belgian territory and was now occupied by a Belgian signalman. However, the rest of the village remained in German hands but was cut off from the rest of the country by the railway. Hemmeres had become an exclave. 

Dynamited

From late 1944, trains would never again cross the Vennbahn near Hemmeres. When the German army fled the Allied troops in the final stages of World War II, the engineers blew up the brick viaduct over the Our River. The bridge abutments along both banks remained upright, but the railway bridge was never repaired. 

After World War II, Belgium was also granted the territory of the village of Hemmeres itself. It was only in 1956 that Hemmeres was given back to Germany. Now, the Our River forms the border between Belgium and Germany.