Warmaster-class Titan - Notable Campaigns: Schism of Mars (005-006.M31) - In the opening solar months of the Horus Heresy, the true depth of the Warmaster Horus' treachery was revealed. Nine Space Marine Legions turned against the Emperor, and across the galaxy, innumerable worlds cast aside their oaths to the Imperium in favor of His once favored son. Even the leader of the ancient Mechanicum -- Fabricator-General Kelbor-Hal -- had been lured down treasonous paths, plunging the Red Planet into war after receiving promises of access to technologies the Emperor had long deemed forbidden. Of those Titan Legions stationed on the Red Planet, of which nearly two dozen were present when conflict gripped Mars, the most prominent were those of the Triad Ferrum Morgulus, the first three Titan Legions ever raised.  Rivalry between the Legio Ignatum, the Legio Tempestus and the Legio Mortis was all too common and quickly escalated into bloodshed during the Horus Heresy.  Indeed, Legio Mortis, ever-loyal enforcers of the fabricator-general's will, proved eager to lay low their erstwhile allies. With brutal efficiency, battlegroups of the Death's Heads Titans fell upon those forge-fanes guarded by the Fire Wasps in an effort to exterminate all pockets of potential resistance on the red planet. At the forefront of the Legio Mortis forces strode newly awakened Warmaster Titans, their presence marking the new era of bloodshed that had fallen upon the galaxy. In its wake, Mars plunged into civil war, the Traitors' victory so complete that word of the existence of a new class of god-engine would not reach Terra until the Horus directly threatened the cradle of Humanity during the Siege of Terra.Siege of Taravo'Anor (Unknown Date.M31) - Located in the northern reaches of the Segmentum Obscurus, Trav'anor was an oddity in terms of a Mechanicum holding. An Industrial World, Travo'anor was rediscovered during the Great Crusade. Its people were eager to take their place in the burgeoning Imperium and to share their own knowledge with that of the Mechanicum. In time, the planet became a chief producer of armaments in the Segmentum Obscurus, serving as a vital resupply point for expeditionary fleets moving to the war front. By the time of the Horus Heresy, Travo'anor maintained ties with multiple Forge Worlds, from which its production capabilities vastly benefitted. Repeated attempts had been made, both by Mars and numerous other prominent Forge Worlds, to bind the planet to a single Mechanicum enclave. This was ardently resisted by the people of Travo'anor, who favoured no one side over the other. To gain favour, many Forge Worlds were granted permission to build forge-fanes upon the planet and its moons, providing them a base of operations. Many Forge Worlds took this as an opportunity to garrison Titan demi-Legios and other military forces in preparation for forays into the Segmentum Obscurus. In turn, Travo'anor was well-protected, with nearly a dozen Titan Legions having established a presence on the world during the later years of the Great Crusade. The diplomatic efforts of Travo'anor proved problematic when Horus' treachery was revealed, with the loyalties of the invited guardians split between the two sides. The most prominent of Loyalists stationed upon Travo'anor proved to be those of the Legio Destructor, Legio Ignatum and Legio Crucius, three Titan Legions of much renown. These Titan Legions were noted for their forward planning and had long-prepared for the escalation of tensions amongst rival Mechanicum factions both on Travo'anor and elsewhere. As such, their own forge-fanes were considerably reinforced, and the true extent of military forces deployed there was concealed from all but their own. Though none could have predicted the scale of conflict unleashed by the Horus Heresy, their move towards increased security proved prudent, for many of Horus' allies greatly desired the planet's resources. The moons of Travo'anor soon saw open war as Titan Legions turned upon one another and Traitor forces moved to secure the Industrial World. A significant battle during the opening days of the Siege of Travo'anor was centered around the forge-fane of Novavistra, capital of the planet. It was here that the leadership of Travo'anor sat, and thus it proved a priority target for the Traitor forces. When assaulted by more conventional ground forces failed, the Traitors moved their Titan Legions in, hoping to decapitate the leadership of Travo'anor before they could flee. In response, the Loyalists -- who were hard-pressed across multiple fronts -- unveiled their masterstroke. As several maniples of Traitor Titans advanced on Novavistra, Titan Landers transported a handful of Warmaster Titans, drawn from four different Titan Legions, in their path. Sent to Travo'anor to serve should a dire need arise within the Segmentum Obscurus, the behemoth god-engines were all that stood before the advancing Traitors and the evacuating forge-fane. Though greatly outnumbered, the Warmaster Titans quickly proved they were far from outgunned.