Avenging Sons - Notable Campaigns: Space Port on Archimedon (Unknown Date.M41) - The world of Archimedon was the place where a major engagement of the Avenging Sons' 3rd Company unfolded. Their mission was to defend a spaceport on the planet. However, after the battle turned against them, they destroyed the spaceport themselves rather than let it fall into enemy hands. The Chapter Master of the time disagreed with this course of action, but he did not formally punish the company. The 3rd Company suffered substantial losses in this battle, including their Chaplain (who was replaced afterwards by Chaplain Herdain) and these losses helped to prime the company for the betrayal of the Emperor they would carry out on the world of Helmabad.Helmabad Rebellion (970.M41) - The Avenging Sons' Captain Gessart and his 3rd Company turned Renegade whilst fighting in the civil war on Helmabad against a force of Chaos Cultists, who had stirred up a rebellion against the Emperor, to save their own lives when the course of the battle went against them. Killing their Chaplain and those Loyalist battle-brothers who would not follow them, the Space Marines of the 3rd Company negotiated with the Traitors for safe passage to their Thunderhawk in return for leaving the Planetary Governor undefended for the cultists to slay. After fleeing the planet, which had been struck by a Warp Storm, the 3rd Company painted over their Chapter badges and other Imperial symbols and set course for the Eye of Terror. It should be noted that Captain Gessart intended to continue fighting for the good of humanity, yet could not remain as part of the Avenging Sons Chapter after he had allowed the elimination of those Space Marines who had refused to abandon the world of Helmabad to Chaos to save their own lives. This event has left a nigh indelible stain on the Chapter's honour. The renegade Astartes of 3rd Company have been sighted on at least three separate occasions between 996.M41 and 998.M41 in the vicinity of the Cadian Gate, each sighting moving ever closer to the Eye of Terror.Liberation of Antillis IV (Unknown Date.M41) - The Avenging Sons' 2nd Company led by Force Commander Selleus took extremely heavy casualties during the Antillis IV campaign to recover that world from the forces of Chaos. Outnumbered by a Chaos force led by a warband of Chaos Space Marines of the Black Legion, the detachment was ground down and eventually surrounded. Their defences broken, they fought to the end, detonating their position just at the moment of being completely overrun. The only known survivor was a single member of an attached Scout Squad and a Thunderhawk gunship which contained a large portion of the company's precious gene-seed, extracted during the battle.Taros Campaign - First Taros Intervention (998.M41) - A strike force composed of the Avenging Sons' 2nd Company fought in the first Imperial intervention that began the Taros Campaign on the desert Mining World of Taros in the Ultima Segmentum. The Avenging Sons' Captain Armaros led a Kill-team comprising a single reinforced company of the Avenging Sons to Taros in order to execute Planetary Governor Uphir Aulis within the Governor's Palace for his traitorous dealings with the T'au Empire, but the Space Marines were surprised by Taronian Planetary Defence Forces and a large contingent of T'au Fire Warriors who were secretly on the world to try and seize it from the Imperium. As a result of the unexpectedly large presence of the T'au Fire Caste on Taros, the Avenging Sons' mission failed and they had to extract themselves from the world with heavy casualties, including the loss of a Dreadnought.