400th Assault (Clan Steel Viper)

Clan Steel Viper.jpg
Four Hundredth Assault Cluster
Disbanded By Feb 3076[1]
Nickname The Diamondbacks
Affiliation Clan Steel Viper
Parent Command Alpha Galaxy


The 400th Assault Cluster was formed specifically to provide Alpha Galaxy with an assault unit. They originally fielded King Crabs and Highlanders, and were later re-equipped with Crossbows and other assault OmniMechs.[2]

Operation Revival[edit]

On the 21st of November 3051, the 400th Assault Cluster landed on Benfled and defeated the defending Narhal's Raiders in four hours of pitched battle, costing the mercenaries two thirds of their forces. During breaks in the fighting, the 400th reconfigured their OmniMechs to confuse the Raiders' estimates of their capabilities.[2]

Post Invasion[edit]

After Tukayyid, the 400th absorbed most of the survivors of the 250th Assault Cluster.

In November 3052, the 400th invaded Blair Atholl together with the Fourth Viper Guards. The two Clusters decimated the Jade Falcons' Eighty-Ninth Striker Cluster and forced the remnants of the Ninety-fourth Striker to retreat off world.

The 400th Assault and the Fourth Guards paired up again in September 3053 to invade Graus in search of a rumored Star League cache. There, they again faced the Eighty-ninth Striker, as well as the Fourth Falcon Velites. Despite taking heavy casualties, the Steel Viper forces succeeded in conquering the planet.

In 3054[3] the cluster was stationed on Blair Atholl along and were still defending the planet in 3060.[4]

Ejection from the Inner Sphere[edit]

In 3061 during the Clan Steel Viper assault on the Clan Jade Falcon Occupation Zone they were part of the fighting on Waldorff,[5] which ended with the ejection of Clan Steel Viper from the Occupation Zone. By 3067 the cluster had moved to Homer.[6]

The Wars of Reaving[edit]

While the final fate of the 400th Assault Cluster is not detailed, Alpha Galaxy was among the Steel Viper forces that defended New Kent, the last Steel Viper holding, during the Trial of Annihilation that saw the Steel Vipers destroyed. As the Trial was declared to have been completed on 10 February 3076, the 400th had been destroyed by this point in time.[1]


Rank Name Command
Commanding Officers of the 400th Assault
Star Colonel Kimberly Hoskins 3057[7]
Star Colonel Liam Callaghan 3061 - 3067[7][6]


The Crossbow OmniMech design featured highly in the Krait and Boa Stars in 3061.[7]



400th Assault Cluster [8]

  • Cluster Command Star (1 OmniMech Star)
  • Trinary Alpha (3 OmniMech Stars)
  • Trinary Bravo (3 OmniMech Stars)
  • Trinary Charlie (3 OmniMech Stars)
  • Trinary Delta (1 OmniMech/Elemental Nova, 2 Elemental Stars)
  • Trinary Echo (3 OmniFighter Stars)


400th Assault Cluster - Veteran/Reliable [7]

  • 5 Trinaries


400th Assault Cluster - Elite/Reliable [6]

  • 95% full strength and fully equipped with OmniMechs



  1. 1.0 1.1 The Wars of Reaving, p. 150-151 - "Focused Aggression"
  2. 2.0 2.1 Era Report: 3052, p. 59
  3. Objective Raids, p. 30
  4. Field Manual: Warden Clans, p. 165
  5. ”Falcon Rising”p.232
  6. 6.0 6.1 6.2 Field Manual: Update, p. 79
  7. 7.0 7.1 7.2 7.3 Field Manual: Warden Clans, p. 143
  8. Invading Clans, p. 94