The 73rd Epsilic Eagles became famous throughout the Varinus System for their well organised defence against a series of realspace raids from the Kabal of the Dying Sun. The sinister Archon Vorl-Xoelanth had been spearheading vicious attacks against the population of two worlds in particular: Nusius II and III. The local Astra Militarum regiments proved too slow to keep pace with the Dark Eldar, and those who were not killed outright ended up being transformed into experiments for the Haemonculi covens. Segmentum Command ordered the 73rd Epsilic Eagles to maintain a vigilant presence in the system, so that they might rush to the defence of the cities in which the Kabal of the Dying Sun had struck. Though the 73rd Epsilic Eagles never killed Vorl-Xoelanth, their rapid responses, expertly coordinated, saved thousands of Imperial citizens from being claimed as prisoners and tortured to death in horrifying ways within the bowels of Commorragh.
When sightings of a Dark Eldar Raider came from the shrine slums of Nusius II, the 73rd Epsilic Eagles dropped en masse from their Valkyries, deploying via grav-chute to surround and eliminate the raiding party. Their mag equipment enabled them to launch attacks on clutches of Kabalite Warriors, approaching from angles and heights for which the swift Dark Eldar had not planned. These sudden, unexpected blows slowed down the Dark Eldar greatly, allowing wider Imperial forces to be mustered. Together the Scions and Astra Militarum troopers were able to drive the remaining warriors of the Kabal of the Dying Sun from the planet, and the Dark Eldar raids eventually ceased in the Varinus System altogether.
The Tempestus Scions of the 73rd Epsilic Eagles primarily wear tan-coloured fatigues, with green-coloured camouflaged Carapace Armour with silver-coloured trim, as well as green-camouflaged coloured knee guards and Omnishield Helms. The Slate Monitron is tan in colour. A green beret is often worn in lieu of an omnishield helm when not in battle.
The regimental symbol borne by the 73rd Epsilic Eagles is a heavily stylised fist known simply as the Gauntlet. The reason for this symbology is known only to the regiment's Tempestors, and has never been explained to any outsider. Whether it is a mark of honour, or one of shame, remains a mystery.
- Codex: Militarum Tempestus (6th Edition), pp. 24, 34