Vespasian

Vespasian was one of 2 senior Lord Commanders of the Emperor's Children during the Great Crusade and beginning of the Horus Heresy. Unlike his counterpart Eidolon, Vespasian was immensely likeable, for his incredible abilities as a warrior and commander were tempered by a rare humility that made others warm to him immediately. Following the Cleansing of Laeren, Vespasian took note of the change in character of the Legion as a whole. Over time a rift soon grew between the once-favoured Lord Commander and his Primarch. When Vespasian attempted to seek audience with his lord, his efforts were repeatedly rebuffed. When he eventually confronted Primarch Fulgrim over rot and corruption that plagued the Emperor's Children, he finally realised the full extent of the malign power of Chaos. Fulgrim murdered the Lord Commander with the poisonous blade known as the Kinebrach Anathame.

History
Following the Cleansing of Laeren, the rot of corruption had begun to spread throughout the entirety of the III Legion. Lord Commander Vespasian, one of two senior commanders within the hierarchy of the Emperor's Children, staunchly adhered to his Legion's ethos of perfection of honour, refusing to allow himself to fall to the rampant hubris and arrogance that had become more common within the ranks of the Emperor's Children. Over the course of many months, Vespasian consulted other like-minded Battle-Brothers within the Legion, including 2nd Company commander Solomon Demeter, about his growing concerns and fears for the future of the Legion.

Vespasian was present during the meeting between Ulthwé Craftworld Farseer Eldrad Ulthran and his Primarch Fulgrim upon the Eldar Maiden World of Tarsus. He had heard the the dire warning presented to them of the Warmaster's corruption to the then-unknown dark powers of Chaos and the inevitable rebellion that would soon follow. The Primarch had rejected such accusations as outright heresy and, influenced by the corrupted daemonblade of the Laer, Fulgrim ordered his delegation to attack the upstart Xenos. Lord Commander Vespasian reluctantly followed his Primarch's orders and destroyed Tarsus and the rest of the Maiden Worlds the 28th Expeditionary Fleet had recently encountered through Exterminatus. Weeks later, Fulgrim's fleet was ordered by the Council of Terra to rendezvous with the Warmaster Horus's 63rd Expeditionary Fleet to inquire about reports of the their recent conduct and acquire information in regards to Horus's grave injuries sustained on Davin's feral moon. Vespasian was excluded from this delegation with the Warmaster, further demonstrating the growing rift between the Lord Commander and his Primarch Fulgrim.

Following this delegation to the 63rd Expeditionary Fleet, Fulgrim announced to his senior commanders that he would lead a small force to join Ferrus Manus and the Iron Hands X Legion at Callinedes IV in the Callinedes System under the pretense of clearing it of an Ork infestation. The rest of the Legion would rendezvous with the Warmaster’s 63rd Expedition at the Istvaan System to halt a growing rebellion. But the III Legion wasn't to fight alone, for they were to deploy alongside the Death Guard and the World Eaters. Though the men of his Legion cheered in adulation at the prospect of fighting with their brother Astartes, Fulgrim's amusement turned instantly to sorrow as he understood that, but for Vespasian’s stubbornness, a great many of these warriors would have made a fine addition to the army of the Warmaster’s new crusade. With such warriors fighting for the Warmaster, what heights of perfection would have been beyond them? Vespasian’s refusal to allow his men to sample the heady delights of Chief Apothecary Fabius’s chemical stimulants, or to undergo his enhancing surgeries, had condemned the warriors once under his command to death in the Warmaster’s trap of Istvaan III. He realised he should have disposed of Vespasian much sooner, and the mixture of guilt and excitement at the deaths he had set in motion was a potent cocktail of sensations. When the killing on Istvaan III was done, the chaff would have been cut from Horus’s force, and they would be a sharpened blade aimed at the heart of the corrupt Imperium.

Vespasian met his end after the operation conducted by the III Legion to cleanse Callinedes. The Lord Commander was denied audience with the Primarch, a most unusual occurrence, after numerous requests. A dark shroud had hung over Vespasian ever since the battle on the deep orbital of the Callinedes system. The Primarch spearheaded the assault during the pacification of Deep Orbital DS191, leading the 1st, 2nd and 3rd Companies. During the assault, Captain Solomon Demeter, commander of the Emperor's Children 2nd Company, found himself unsupported by the 1st and 3rd companies as the battle-plan had laid out. Overextended and in real danger of being cut off and destroyed, the 2nd Company was only saved from certain destruction by the unplanned and timely arrival of the 10th and 13th Companies under the commands of Captains Saul Tarvitz and Lucius, two junior officers that Demeter had found himself associating more and more with as he was systematically frozen out by Legion high command. A dark shroud hung over the Lord Commander since witnessing these events as he felt obliged to act after he observed Solomon Demeter's 2nd Company being intentionally abandoned by both Captains Kaesoron's and Vairosean's companies.

Within hours, the 2nd Company had been in transit to the Istvaan System to rendezvous with three other Legions to pacify the rebellious world of Istvaan III. Finally seizing the opportune moment, Vespasian confronted Fulgrim in his stateroom over the growing corruption and decay of the Legion's ideals that they had been founded upon. The Lord Commander discovered, much too late, the malign influence of Chaos that had held sway over his Primarch. With sibilant whispers of the daemon-possessed Laer sword urging him on, Fulgrim murdered Vespasian in cold blood by stabbing him in the neck with the Anathame that had been gifted to him by the Warmaster.