In February 1938, while in the Monzón area, it was sent to the Teruel front to aid the republican forces stationed there. After its arrival, on February 12 it attacked the nationalist positions in La Torana, without success. Between the 24th and 28th it had to face new nationalist attacks in this area, after which it withdrew to the plains of Valdecebro. Subsequently, the 125th MB took part in the Aragon and Levante offensives, where it had to withdraw on several occasions due to enemy pressure. By July 24, it was located at the XYZ Line, in Viver-Jérica. However, due to the heavy losses suffered, it had to be withdrawn to Chelva.