From Lexicanum

Commissars are special Imperial officers assigned to Imperial Guard regiments, whose purpose is to enforce discipline and devotion to the Emperor within the regiment.

Commissars are invariably stern and uncompromising individuals, able to keep even the most anarchic regiments in line through fear, strength and power. Every regiment has one or more attached Commissars who remain with the regiment throughout its duties. Commissars are assigned to regiments by the Departmento Munitorum, which provides high-ranking commanders to Imperial Guard armies. They have authority over both the soldiers and regimental officers. Commissars have both the right and duty to immediately execute any Imperial guardsman or officer who shows cowardice or incompetence in battle. They must also ensure the regiment does not harbor the likes of Genestealer Cultists, Chaos heretics, spies, or mutants.¹

Personnel selected to become cadet Commissars are drawn from the Schola Progenium - Ecclesiarchy-run schools, where the pupils have already received a strict Imperial cult education.

Cadet Commissars are given the standard arms and equipment of a Guardsman, although they retain their distinctive uniforms. These uniforms differ from those of a full Commissar by featuring blue trim and a specific Cadet emblem. Their training has no set duration and a Cadet will be graduated as soon as he is deemed worthy. Part of the training of a Cadet-Commissar emphasises learning standard infantry tactics and gaining experience in situations common to standard Imperial Guardsmen. In order to ensure this, Commissar-Generals may decide to form up the Cadets under their purview into Training Squads, 9 Cadets under the command of a specially chosen full Commissar.

Commissar Training Squads are groups of Cadet-Commissars, formed up into a fighting squad and led by a full Commissar into battle. These Cadets are then trained, under battlefield conditions, in how to live, fight and even die alongside the troops they are supposed to one day inspire and discipline. They are sent into the fiercest fighting, in which they are expected to show bravery and devotion enough to earn the respect afforded to them by standard troopers. Commissar Training Squads are highly motivated and pious fighting units and an Imperial Guard force accompanied by such a squad will consider itself destined for victory.

When a Commissar decides that a Cadet has failed in his duty to become a Commissar, but has not shown cowardice or insubordination, the Cadet is relieved and may be either sent to a Stormtrooper unit or become an officer in a penal battalion. Others volunteer for service in a Rogue Trader's entourage, and others may face darker destinies.

Commissar-Generals are senior and highly experienced Commissars, having the additional responsibilities of assigning the Commissars under his command to regimental officers and promoting cadets to full Commissar status.²

Colonel-Commissar

Colonel-Commissar is a rare rank of the Imperial Guard, held usually in only extraordinary cases. Though the records show the rank being held as recently as the Sabbat Worlds Crusade (Ibram Gaunt) the inherent clash between the two roles is normally seen as a threat to a regiment's discipline - Commissars maintain discipline and watch commanders, the commander leads the regiment in combat - the two roles are technically exclusive.³

Famous Commissars

• Commissar-General Delane Oktar³
• Colonel-Commissar Ibram Gaunt³
• Commissar Fidel Arden²
• Commissar Ciaphas Cain⁴
• Commissar Severinus
• Commissar Yarrick⁵

Sources

• ¹:Codex Imperialis
• ²:White Dwarf 115, 1989, Commissar Training Squads, reprinted in Warhammer 40,000 Compilation, 1991
• ³:Gaunt's Ghosts (Novel Series)
• ⁴:Ciaphas Cain (Novel Series)
• ⁵:Codex: Imperial Guard (3rd Edition, 1st Codex)

Codex: Imperial Guard (3rd Edition, 2nd Codex)

Imperial Guard Infantry
Command Units	Command Platoon • Heroic Senior Officer • Senior Officer • Junior Officer • Sanctioned Psyker • Commissar • Priest
Flexible Troops	Infantry Platoon • Conscript Infantry Platoon • Hardened Veteran Squad • Storm Troopers • Sentinel Squadron
Combat Troops	Armoured Fist Squad • Rough Rider Squadron • Ogryn Squad
Ranged Troops	Ratling Snipers • Snipers • Heavy Weapons Platoon
Support Units	Fire Support Squad • Anti-tank Support Squad • Mortar Support Squad • Sentinel Support Squadron Special Weapon Support Squad • Techpriest Enginseer