The opening of the branch to Otterbach in 1911, and the Bach Railway (Bachbahn, so called because all of its stations had names ending in “bach”, i.e. “brook”) to Weilerbach, which was extended in 1920 to Reichenbach, gave the Lauter Valley Railway greater importance, especially its southern stretch, since the passenger trains on either route often continued to Kaiserslautern. On 1 November 1917, during the First World War, the intermediate stops in Kaulbach and Lohnweiler were closed. Eleven months later, however, they were reactivated. In 1920, the line became part of the newly founded Deutsche Reichsbahn.
