The Knights Unyielding is one of the Loyalist Space Marine Chapters founded as part of the Astartes Praeses -- one of the 20 Chapters of Astartes mentioned in the ancient tome known as the Mythos Angelica Mortis that was created to defend the regions surrounding the Eye of Terror in the Segmentum Obscurus from the Forces of Chaos. The Knights Unyielding are of an unknown Founding and origin.
The Knights Unyielding's Chapter colours are not recorded in current Imperial records, though they are noted for wearing highly ornamental armour plastered with purity seals and fluttering oath papers.
The Knights Unyielding's Chapter badge is not recorded in current Imperial records.
- Dark Creed (Novel) by Anthony Reynolds, pg. 45