Heathcliff Erbe was as an Ishvalan cadet around the same time that Roy Mustang and Maes Hughes also enlisted in the military. Heathcliff joined in hope of becoming an officer and eliminating discrimination from within in the military, much like the motivations of Major Miles, another Ishvalan soldier.

Due to his race, many other soldiers constantly harassed and threatened Heathcliff.

(Source: FMA Wiki)