The Fire Hawks was one of the Loyalist Space Marine Chapters created in the 36th Millennium during the Cursed 21st Founding. While the Fire Hawks have always maintained they were forged from the genestock of the Ultramarines, certain defects and variations in the samples of Fire Hawks gene-seed still held in the archives of the Adeptus Terra speak against this. Furthermore, the sons of Roboute Guilliman have never acknowledged any kinship, fueling suspicions as to their true heritage.