Complex sentence: In March 1937 the brigade took part with success in the Battle of Guadalajara and in April it was was sent again to attack the Cerro de los Ángeles, ending again in failure.
Split into simpler sentences: In March 1937 it took part with success in the Battle of Guadalajara. In April it was was sent again to attack the Cerro de los Ángeles, ending again in failure.