Members of the Fire caste are the warriors of the [[Tau Empire]], and as such are most often seen on the field of battle. They are taller and stronger than the members of the other castes, although still weaker and shorter than the average human. These traits come from the Fire Caste's origin on the plains of T'au, where they were hunters and warriors. Tau from the world of [[Vior'la]] tend to have slighter greater muscle mass than the norm because of the stronger gravity of that planet. These warriors are known as [[Fire Warrior]]s.

Provided the warrior survives 4 years of ''active duty'', he undergoes the first [[Trial by Fire]], which can be anything from mere gladiatorial affairs to trial by constant combat. If the Shas'la survives his first Trial by Fire, he is promoted to the rank of Shas'ui, or Veteran. For every consecutive four years of service, the Fire Warrior undergoes another Trial. The higher one's rank within the Fire Caste, the more likely one is to be a [[Battlesuit]] pilot. Upon attaining the rank of '''"O"''', a member of the Fire Caste may be allowed to retire from active duty and become an advisor to the Tau military's command structure, the [[Shas'ar'tol]]. Other than death this is the only way to leave the Tau military.