[3] On 9 March 1937 the 49th Mixed Brigade had its baptism of fire at the Guadalajara Front, where it became part of the Republican forces that fought the Fascist Italian Corpo Truppe Volontarie.

On 3 April the unit found itself at the breaking point of the front which was submitted to vehement attacks by the forces of rebel general Antonio Aranda and it had to withdraw from the first line after being badly shattered.

On 30 May the 49th Mixed Brigade was again very hard hit fighting the rebel Levante Offensive in the Ares del Maestrat-La Jana sector.

Towards the beginning of July the much depleted unit was defending Castellón under the command of Infantry Major Amado Granell, but on the 15 it was definitively withdrawn for its reorganization.

Following the Levante battles Militia Major Fernando Gil Ferragut became the new leader of the unit and the brigade was transferred to the less active southern front of the Levantine Army.

There were so many dead among the members of the 49th Mixed Brigade, that the Republican high command desisted from reconstituting it, distributing the survivors among other military units.