The soldiers of the Imperial Fortress World of Cadia form the Cadian Shock Troopers regiments of the Imperial Guard, famed throughout the Imperium for their skill and discipline. They stand as the front line of defence against the predations of Chaos, staring into the very gates of hell, the courage of Cadia's soldiery having repeatedly saved the Imperium from the rampages and depredations of the Forces of Chaos. Amongst the most illustrious of regiments the Cadian 8th stands at the fore. Its low designation indicates that it was first founded thousands of years ago, perhaps during the earliest days of the Imperium itself, and has been re-founded many times since to ensure that its glorious heritage never dies. Known as "The Lord Castellan's Own," their commander is no other than the lauded and much beloved Lord Castellan of Cadia, Ursarkar E. Creed.
The 8th Cadian is comprised of approximately 8,000 Guardsmen divided into roughly 24 companies. At least two companies at a time are in hostile environment training on Prosan (the innermost planet of the Cadian system) and two others help to garrison Kasr Sonnen and Kasr Holn (fortress worlds within the Cadian System). Due to their illustrious history and elite status, the companies of the Cadian 8th are in high demand to play support roles for other units or to serve in smaller formations as elite strike forces. As a result, the 8th Cadian rarely fights as an entire unit, instead having its companies deployed as support elements for other, less able Imperial Guard or Planetary Defence Forces. In addition, there is always demand for soldiers of the 8th to be indentured to Inquisitors, particularly members of the Cadian Internal Guard, or to assist in training newly-founded regiments.
The 8th Cadian is equipped with a number of Leman Russ main battle tanks which were deployed to maximum effect during the 13th Black Crusade in 999.M41. The Cadian 8th's officers are also some of the most skilled leaders in the Imperial Guard and are often used to lead the training cadres that will churn out new Cadian Shock Trooper regiments that can meet the high standards required by the Cadian military tradition.
The Cadian 8th is one of the oldest regiments of the Imperial Guard, its low number indicating that it may have been founded in the earliest days of the Imperium, perhaps even dating back to the period before the Imperial Guard and the Imperial Navy became separate branches of the Imperial military following the break-up of the Imperial Army after the Horus Heresy. The Cadian 8th has been destroyed as a functional regiment numerous times following intense combats, but it has always been reformed on Cadia and brought back up to full strength because of its illustrious history of service. The earliest reference to the deeds of the 8th Cadian in existing Imperial records is the Vrakesworld Campaign of the 38th Millennium, though the unit may have been referred to by a different designation earlier in its history.
The 8th Cadian received its highest honour, being named the "The Lord Castellan's Own," during the darkest days of the 13th Black Crusade when their former commanding officer, Colonel Ursarkar E. Creed, was named Cadia's Lord Castellan (Planetary Governor). Creed had served in the 8th Cadian throughout his career and had steadily ascended its ranks over the course of his long career of service. Creed began his service as a young lieutenant in command of a platoon of the 8th Cadian during the Drussite Crusade in 975.M41 and rose to the rank of Lord General when he crushed a raid by the Eldar of Craftworld Ulthwé in 992.M41. When the traitorous Volscani Cataphracts betrayed the Emperor and slaughtered most of Cadia's high command at the Battle of Tyrok Fields on Cadia during the 13th Black Crusade in 999.M41, Creed was appointed to the Fortress World's highest military and political office. The Cadian 8th fought desperately and heroically throughout the 13th Black Crusade, and Creed chose to remain the 8th's commanding officer even as he assumed command of all of the Imperial military forces deployed on the surface of Cadia to throw back the invasion launched by the Forces of Chaos under the command of Abaddon the Despoiler. While Abaddon's forces remain bottled up on Cadia by the Imperial Navy at the present time, the 8th remains at the forefront of trying to purge their world of the taint of the Heretic and the Traitor.
- Vrakesworld Campaign (38th Millennium)
- Gerreck Heresy (40th Millennium)
- The Drussite Crusade (975.M41)
- The Hrud Migration (983.M41)
- 13th Black Crusade (999.M41) - The 8th Cadian Regiment was engaged in multiple battles across the world of Cadia in the midst of Abaddon the Despoiler's all-out assault upon the Cadian Gate during the 13th Black Crusade.
- Battle of Tyrok Fields - During the outset of the Despoiler's 13th Black Crusade, treachery struck at the heart of the Imperium's defences. As the defenders of the Cadian Gate mustered, the traitorous Volscani Cataphracts revealed their true allegiance to the Ruinous Powers. The traitors slaughtered hundreds of loyal Guardsmen before any response could be coordinated. The intent of the Volscani's treason was revealed as they swarmed aboard the the Leviathan command vehicle of the Governor Primus of Cadia and proceeded to slaughter him and much of the senior command of Cadia's armed forces. This included the commander-in-chief of the defenders of the Cadian Gate, who was killed in the brutal attack. At the darkest moment, then-Colonel Ursarkar Creed took control of the dire situation. Rallying the glorious 8th, the bloodied defenders were quickly organised and ordered to advance upon the traitors. The 8th Cadian led the charge into the ranks of the traitorous Volscani. Through Creed's actions, what might have been a grievous defeat for the Imperium, and a nefarious victory for the hordes of the Archenemy, was turned into a defining moment for the defenders of Cadia.
- Ursarkar E. Creed - Colonel and Commanding Officer of the Cadian 8th Regiment; Lord Castellan of Cadia
- Jarran Kell - Ursarkar E. Creed's best friend and Regimental Standard Bearer of the Cadian 8th Regiment
- Codex: Eye of Terror (3rd Edition), pp. 12-13, 40-41
- Codex: Imperial Guard (5th Edition), p. 57
- Codex: Imperial Guard (3rd Edition, 2nd Codex), pp. 10-11, 13, 30, 50-51
- Imperial Armour Volume One, pp. 64, 71, 94, 102, 109, 115, 168, 180, 196, 259
- White Dwarf 283 (US), "Heroes & Villains of the 41st Millennium - Ursarkar E. Creed, Lord Castellan of Cadia" by Pete Haines, pp. 68-73