After the Nazis sunk a fair amount of Brazilian merchant ships, the previously neutral government of Brazil decided to officially declare war on the side of the Allies against the Axis. The Brazilian Navy almost immediately began operations against the Nazi Navy, trying to ensure safe Allied shipping across the Atlantic. Brazil spent a couple years training a sizable foreign army called the Brazilian Expeditionary Force. Eventually 25000+ individuals were trained and by 1944, a few divisions made it across the Atlantic to the Italian theater. The Brazilian soldiers were mainly used as replacements for divisions that were reassigned to other European invasion locations. The Brazilian soldiers were seen as a welcome addition to the Allied troops, as they allowed the reassignment of divisions to fronts where more troops were needed. While the Italian front was by no means easy, it was considered a secondary objective compared to pushing back the German army. After a spectacular victory during the Battle of Collecchio, the Brazilian army, along with other Allied forces, managed to force the surrender of the German Army, mainly due to the simultaneous capture of Berlin by the Red Army.

As for why the efforts of the Brazilian Army are not mentioned in history classes, I don't have a answer. They definitely provided a service to Allied troops, bringing about the end of WWII. I'd put them in the same class as the Indian Army during WWII, volunteers who provided a great service to the Allies, but today are mostly forgotten.

Sources: https://en.wikipedia.org/wiki/Brazilian_Expeditionary_Force

Neto, Richard, Brazilian Expeditionary Force in World War II (2011)