Sergeant (Imperial Guard) - Tiers of Sergeants: The Tactica Imperium only dictates the existence of the ranks of sergeant and veteran sergeant (following the practices of the Adeptus Astartes), but as the need for experience and counsel from the non-commissioned corps is still required at the highest levels of the Astra Militarum's hierarchy, governor-militants have universally adopted the practice of expanding the sergeant rank into multiple other ranks in order to discern one from another within the regiments of the Astra Militarum raised from their worlds:Sergeant - Sergeants are often placed in charge of a squad of guardsmen at the lowest tactical level (platoon).Staff Sergeant - A staff sergeant is the senior sergeant in a platoon. They can also be assigned to the platoon's Command Squad or to an Infantry Squad. Also known as a "platoon sergeant" in some regiments.Gunnery Sergeant - Above platoon level, most gunnery sergeants find themselves in charge of munitions and weapons for a full company, and are usually assigned positions in company command elements, in charge of a squad deemed critical by the company commander, or as the senior enlisted person in heavy support detachments.Master Sergeant - Master sergeants tend to forego the opportunity to become liaisons and advisors to their unit commanders and instead focus on one specific duty, such as logistics and supplies to the frontline, commanding a Leman Russ Tank or Chimera armoured transport vehicle, or being in charge of communications at the company level.First Sergeant - Unlike a master sergeant, first sergeants become liaisons and advisors to their company commander, and use their battlefield experience to recommend tactics and strategies to their commanding officer.Master Gunnery Sergeant (Master of Ordnance) - A master gunnery sergeant, also called a Master of Ordnance, is usually assigned to oversee all logistics, transport, and supply operations of a full regiment or even higher levels of tactical organisation within the Astra Militarum. In combat, master gunnery sergeants are usually assigned to command Leman Russ Tanks, or even on the rare occasion a Baneblade super-heavy tank. Senior master gunnery sergeants will undergo Imperial Naval training as a Communications Officer, and using their knowledge of communications will be assigned to a Command Squad at the regimental level or higher as a Master of Ordnance who is responsible for calling in all of their regiment's air support from the Navis Imperialis' Aeronautica Imperialis.Sergeant Major - Following the path of a first sergeant, the sergeant major is the senior enlisted advisor and liaison to a regimental commanding officer or to an even higher-ranked Astra Militarum officer, and is the senior enlisted person for their entire regiment. When more than one regiment is involved in a campaign, the senior officer, usually a lord general militant, will appoint one of the available sergeants major to the title of command sergeant major, indicating that they are the most senior of the sergeants major within all of the Imperial forces assigned to that theatre of operations for the duration of the campaign. There have been rumors of appointing one sole sergeant major to a new rank called "sergeant major of the Astra Militarum" to act as the Lord Commander Militant of the Astra Militarum's personal liaison and advisor to the ranks, but the selection list would be astronomically long and to date such a rank does not yet exist.