Changes

Kasteen was a captain and the last remaining senior officer of the former 296th Valhallan, an all-female rear echelon regiment, when it was nearly wiped out by the [[tyranidTyranid]]s on [[Corania]]. The regiment was merged with the all-male 301st, a planetary assault regiment, and Kasteen was made the regimental colonel by virtue of three days' seniority over her second-in-command, Major [[Ruput Broklaw]] of the former 301st (who had more combat experience). Tensions between the two former regiments - who continued to use their former regimental identities - came to a head onboard on board the troopship ''Righteous Wrath'' on its way to [[Gravalax]] in 931.M41, in a mess room brawl resulting in the deaths of several troopers and Naval provosts over the use of the 296th's traditional dinnerware. Realizing the situation, [[Commissar]] [[Ciaphas Cain]] - recently assigned to the 296th/301st - had the regiment redesignated renamed the 597th (296 + 301), and the regiment integrated at squad level so that the number of male and female troopers was equally dispersed.

Kasteen led the regiment during the [[Gravalax Incident]], in which the 597th was primarily involved (particularly as Kasteen was present, along with Cain, when the tau ambassador was assassinated in the planetary governor's palace - by the governor himself, as later events proved), and was successful for averting a potential war with the tau based on Cain reaching a rapport with the tau commander. The following year on Simia Orichalae, with Cain's backing, Kasteen declared martial law on the planet - the site of a prometheum [[promethium]] production facility - when it became clear that the [[Administratum]] was unprepared for the defense against the [[orkOrk]] incursion on the planet, and also ordered the planet's evacuation with the discovery of [[necronNecron]] activity beneath the facility. She then aided in the discovery and defeat of a Chaos cult attempting to make the planet [[Adumbria]] into a [[Daemon World ]] five years later, pointing out a pattern in the ritual sites discovered on the surface.