Hailing from the powerful shipping family of House Mesring, Mesring voted in favor of his family's financial interests as opposed to that of humanity's in the Senatorum Imperialis. This included voting against expanding shipyards on Uranus despite their safety in order to protect House Mesring's holdings in the Tang Sector. Mesring was a close ally of the powerful Lord High Admiral of the Imperial Navy Lansung, forming his most important ally among the High Lords alongside Master of the Administratum Tobris Ekharth.
Mesring was highly elitist, slapping subordinates with his obese hand even for looking at his jewelry. However this could not save him from the Grand Master of Assassins Drakan Vangorich, who infiltrated the Ecclesiarchal Palace and poisoned him. Vangorich instructed Mesring that he only had 3 days to live, and if he wanted the antidote he would declare a War of Faith against The Beast and force Lansung to redeploy his fleets against the Greenskins. After Mesring accomplished this, he is still seen alive several weeks later, which was apparently due to somehow acquiring his own antidote as Vangorich intended for him to die.[3b]
Following the appearance of an Ork Attack Moon over Terra and the fall of Lansung from grace, Mesring aligned with the newly ascendant Speaker for the Chartist Captains Juskina Tull. The Ecclesiarch supported the Speaker's disastrous Proletarian Crusade, providing vital vocal support and blessing the operation.[3a] Mesring fell into a deep depression after the operations failure and revealed that he had only acquired enough antidote from Wienand for 25 days. The poisoning shattered his faith in the God-Emperor, seeing Him as enfeebled, and he secretly began praying to the Beast for his show of force. A physically frail and disheveled Mesring later abandoned Lord Commander of the Imperium Udin Macht Udo when he was overthrown by Koorland and the Inquisition.
A visibly unhealthy and unhinged Mesring alongside Ekharth later became the chief opposition to Koorland during his attempts to form the Deathwatch, considering the action heresy. Even after Ekharth and the rest of the High Lords relented to Koorland after the Attack Moon over Terra reactivated, Mesring still voted against the measure. When the Attack Moon shattered and blanketed Terra in debris, Mesring's palace was destroyed by the debris. However he survived and was found in the rubble days later, still screaming.
As Vangorich's poison slowly killed him, Mesring became even more unhinged. Not even the Tears of the Emperor could cure him. Losing the last vestiges of his sanity the day before he was due to die, Mesring confronted Lord Commander Koorland and the rest of the High Lords, declaring him and Vangorich heretics. As he ranted, Mesring eventually declared his belief that the only hope for salvation lies in welcoming The Beast himself, and openly praised the Ork Warlord as a god before the High Lords. With that, he was shot in the head by Koorland. His death went unopposed due to his heretical actions, with Cardinals of the Holy Synod condemning him a heretic. In the aftermath of his death, Koorland stripped the Ecclesiarchy's seat in the High Lords and revoked their privileges. However after The Beheading, the Ecclesiarchy regained its seat when Vangorich appointed Ostulus as a member of the High Twelve.
- 1: I Am Slaughter (Novel) Chapter 9
- 2: Predator, Prey (Novel) Chapter 7
- 3: The Last Wall (Novel)
- 4: Throneworld (Novel), Chapter 21
- 5: Echoes of the Long War (Novel) Chapter 18
- 6: Watchers in Death (Novel) Chapter 4
- 7: The Last Son of Dorn (Novel) Chapters 2-3
- 8: Shadow of Ullanor (Novel) Chapter 2
- 9: The Beheading (Novel) Chapter 13