Oath of Moment

"Do you, Garviel Loken, accept your role in this? Do you promise to lead your men into the zone of war, and conduct them to glory, no matter the ferocity or ingenuity of the foe? Do you swear to crush the insurgents of Sixty-Three Nineteen, despite all they might throw at you? Do you pledge to do honour to the XVI Legion and the Emperor?" -"On this matter, and by this weapon, I swear."

- Oath of Moment administered by Captain Luc Sedirae, 13th Company, Luna Wolves Legion, and taken by Captain Garviel Loken, commander of the 10th Company, before the Battle of the Whisperhead Mountains, 63-19

An Oath of Moment is an ancient tradition that harkens back to the time of the heroic Space Marine Legions during the Great Crusade and Horus Heresy era in the 30th and early 31st Millennia. These were solemn promises, often invoked by several witnesses, usually fellow battle-brothers, regarding an individual's future actions in regards to a sacred vow or pledge to be carried out, no matter the cost. An oath of moment was often carried out before going into battle or setting out on a mission and was taken as a reaffirmation of the sacred oaths sworn to the Emperor of Mankind and a Space Marine's individual Primarch or Legion. A typical oath of moment often required at least two persons - the individual Astartes taking the oath and a swearing battle-brother(s).

The essence of such oaths was an invocation to be a guarantor of the oath-taker's honesty and integrity in the matter under question. By implication, this invokes divine displeasure from an Astartes' Primarch or the Emperor Himself if the oath-taker failed in their sworn duties. Therefore, the import of such a significant pledge implied greater care than usual in the act of the performance of an individual's duty. These pledges usually had an oath-taker taking them over a weapon. Often times these oaths were written on parchment and affixed to the oath-taker's Power Armour before they departed on a mission.

A Space Marine squad often swore an oath of moment collectively, but an isolated Space Marine could swear one simply by declaring it aloud during the heat of battle on an uncaring battlefield or even in his own mind to steel their resolve, with the Emperor as his witness. Some Legions kept these oath parchments as a record of tasks achieved while other more than likely disposed of them ceremoniously or discard them after after they had achieved their promise and were no longer relevant. The Space Wolves for example, often eschewed the use of such oaths, scorning the idea of writing them down. As one Long Fang in the novel "Prospero Burns" by Dan Abnett pointed out, "That's what memories are for."

A few Chapters of the Adeptus Astartes in the modern 41st Millennium still make use of this bygone tradition, such as the Blood Angels and the Iron Knights.