Many of these formations were composed of the first genetically-engineered soldiers the Emperor of Mankind created during that conflict whom He had raised from the first Terran techno-barbarians to swear themselves to His cause.
After Terra was unified and the Emperor embarked upon the Great Crusade to bring all the scattered colony worlds of Mankind across the galaxy under His rule in the newborn Imperium of Man, these regiments were dubbed "the Old Hundred" by the thousands of new regiments raised for the second-line forces that were the Imperial Army.
The Old Hundred were always viewed with the utmost respect and honour by both the other forces of the Imperial Army and even by many of the Terran-born Veterans of the Space Marine Legions who had once fought beside them.
Notable Regiments of the Old Hundred
- Byzant Janizars
- ConFed Gun Brotherhoods
- Cordesh Cavalry
- Geno Two-Five Chiliad
- Kushtun Naganda
- Lucifer Blacks
- Inferallti Hussars
- Ouranti Draks
- Qui-Helic Guard
- Sidthu Barat
- Thorosian Voltigeurs
- Tupelov Lancers
- Uralian Stormlords
- Legion (Novel) by Dan Abnett, Ch. 1
- The Outcast Dead (Novel) by Graham McNeill, Ch. 11
- The Solar War (Novel) by John French, Ch. 7
- The Horus Heresy - Book Five: Tempest (Forge World Series) by Alan Bligh, pg. 177
- Warhammer Community Online - The Siege of Terra Continues