Legio Tempestor - Great Crusade: With the coming of the Emperor to the Red Planet and the signing of the Treaty of Mars, the Legio Tempestus took its place in the glorious hosts of Mankind's all-conquering armies. Tempestus engines walked upon worlds the length and breadth of the ever expanding Imperium, serving alongside some of the most celebrated forces of the Great Crusade.Individual maniples were detached to Mechanicum Explorator fleets and Rogue Trader Militant pathfinder squadrons, but the bulk of the Legio's most celebrated battle honours were earned during service with the 12th Expeditionary Fleet, in what some historians later dubbed the "Long March to Ultramar." Later on, when the Lord of Ultramar, the Primarch Roboute Guilliman, took personal command of the 12th Expeditionary Fleet, the Tempestus played a pivotal role in the arduous wars of the Epsiloid Binary Cluster.It was during this epic conflict that the Legion's master, Princeps Senioris Indias Cavalerio, earned the title "Stormlord," a name soon used by allied Imperial soldiers to refer to the entire Legion and which was thought to echo ancient myths. The term was appropriate, for the Stormlords had proven themselves masters of planetary assault under enemy fire in hostile circumstances many other princeps would never have allowed their own forces to be risked at such hazard.Cradled in the shielded holds of the very heaviest classes of drop transport constructed in the orbital void-factories on Mars, the Legion's brutal descents into battle, shrouded by the fire and storm-turbulence of the drop ship's almost suicidal trajectories, became legendary.They caused atmospheres to burn and made such ruin of the skies that on some worlds the storms they caused would not fully abate for years. Where the Stormlords walked, cities were shattered and battlefields were swept of the foe by a blistering hail of ordnance.After an abated campaign of six solar decades on the forefront of the Great Crusade, the Legio Tempestus suffered heavy losses -- including Victorix Magna, the Warlord Titan of the Stormlord himself -- and needed time to regroup and rearm or risk destruction.Having claimed warden right over key worlds in the Estaban and Orestes Systems, the Legion's master, Cavalerio, returned to Mars with those of his Legion's god-engines in most need of repair and refit, entrusting command of the remainder of a reorganised demi-Legio to his lieutenant, Princeps Maximus Karania.Thus would begin a chain of events that would lead to a growing rift, more a development of circumstance and distance than any actual acrimony or malice, between the two halves of the Legio Tempestus. In the years that followed, two separate commands developed, with little direct contact between them, each being supplied separately and fighting their wars apart under the light of far distant stars.The Martian Tempestus began to be deployed as a heavy reserve, called to battle from their base on Mars to re-enforce the line in the most precarious war zones and to punish rebellious worlds before swiftly returning to their home, while Karania's command would pass from the order of battle of one far-flung Expeditionary fleet to another, never seeing the light of Sol.