The rank and title of First Sergeant is a senior non-commissioned officer's rank used mostly by army organizations. They are highly regarded as both experts in their particular field and natural leaders.
In New Republic Service Edit
First Sergeants in the New Republic Army hold the same pay grade as a Master Sergeant. However, with usually around fifteen standard years of service, First Sergeants are one of the most vital assets a company can have. If the Platoon Sergeant is the "Platoon Father", then the First Sergeant is the "Father of the Company". They are ultimately responsible for everything that the company does, whether it is training, missions, or personnel. It is their responsibility to ensure that all soldiers meet the standards set by the CO and the Director of Ground Operations.