Mathieu was the Militant-Apostolic that served Lord Commander Guilliman during the Indomitus Crusade.
Before he attained his current title, he was a Priest of the Acronite Mendicants, which is a sub-order of the Missionara Galactica. After the Terran Crusade Mathieu was among those trapped on the Macragge's Honour after its capture by the Red Corsairs. During the vessels capture Mathieu was essentially a thrall of the Renegade Space Marines, but in secret held prayer services to the Emperor at great personal risk. Mathieu displayed apparent psychic ability similar to that of a Living Saint when he channeled the power of the Emperor to exorcise a Daemon from a child aboard the vessel. Mathieu displayed confidence after the episode that the Macragge's Honour would soon be freed.
Mathieu was eventually freed and went on to take part in the Indomitus Crusade. There he would give sermons to its masses and fought alongside the Astra Militarum. It was these actions that brought him to the attention of Lord Commander Guilliman when he sought a new Militant-Apostolic after the death of the previous holder Geesan. Though at first Mathieu was hesitant to take the title due to being believing he was unworthy and simply having a desire to do the Emperor's work, Guilliman told him it was these qualities that made him an ideal candidate. After some further consideration[1a], Mathieu accepted and gave a ceremonial speech following the Crusade's victory at Raukos. Afterwards the Crusade was disbanded[1b] and Mathieu was among the Imperial forces Guilliman led to aid the Realm of Ultramar during the Plague Wars[1c]. Despite his title, though, Mathieu took part in the battles of the Plague Wars and wrote a record of Guilliman's exploits against the Chaos God Nurgle's forces.
On Iax Mathieu would lead an army of Frateris Militia, spreading word of both the Emperor and Guilliman's divinity in defiance of the Regent's wishes.[4a] During the final battle on Iax Mathieu took part in the assault to capture the portion of the Cauldron of Nurgle held by Ku'gath and apparently became a Living Saint for a time, channeling the power of the Emperor to shield Imperial servants before destroying the Cauldron himself.[4b] The dying Mathieu was later brought back into orbit to meet with Guilliman one last time, stating that the Emperor was reawakening and that his part in the Emperor's plan was finished. As Mathieu died Guilliman declared that the Imperium would remember his sacrifice.[4c]
While Mathieu believed himself to be a modest man, he did have some ambitions that he did his best to hide. The main source of this was Mathieu's hope to be the person that could convince Lord Commander Guilliman to accept his inherent divinity, as a son of the God-Emperor.[1b] Mathieu seems to have succeeded somewhat, with Guilliman questioning his previous beliefs by the end of the Plague Wars following his own miraculous rebirth on Iax.[4c]
Though a connection has not been confirmed, Militant-Apostolic Mathieu shared his name with the Mathieu family who formed a lineage of Imperial Navy Captains in the Battlefleet Gothic, traditionally commanding the Excellent until its destruction in the Battle of Gethsemane.
- 1: Dark Imperium (Novel)
- 2: Dark Imperium: Plague War (Novel), Chapter 1
- 3: His Will (Short Story)
- 4: Godblight (Novel)
- 5: Shadow Point (Novel), Epilogue