Nathan Armstrong was the first "outsider" to command the entire Eridani Light Horse. Born into a poor family in the Lyran Commonwealth, he was orphaned in a Kurita raid. A Light Horse family adopted him, and he trained as a MechWarrior. Armstrong joined a reconnaissance lance at the age of 18, and displayed remarkable fighting ability.
Armstrong succeeded Brevet General Kerston as commander of the Eridani Light Horse in 3023. One of his first acts was to organize the defense of the planet Hoff, which was targeted by Wolf's Dragoons on behalf of House Kurita.
- "MercHandbook1", p. 72 - Nathan Armstrong's early years
- "MercHandbook1", p. 74 - Colonel Robert Fairchild's biographical capsule notes that he succeeded Armstrong as head of the 151st
- "MercHandbook1", p. 70 - The Battle of Hoff
- "Field Manual: ComStar", p. 87 - Clashing with Wolf's Dragoons
- "MercHandbook1", p. 74 - The Light Horse's personnel roster identifies Armstrong's BattleMech