|Conflict||Unification Wars/Great Crusade|
| Imperial Army
|Boeotian rebel forces|
|Selud (r)||King Kadmus(KIA)|
| Tupelov Lancers regiment
Thousand Sons legion
|Unknown||Extermination of Yeselti genetic line|
Resisting unification with the Emperor, instead, the Yeselti clung onto their independence to the point where, firstly, the Imperial Army was forced to invade the province and finally, Legiones Astartes of the Thousand Sons were assigned to quash the truculent little state.
The campaign to seize the Boeotian citadel took around six weeks. In their final stages of resistance, the rebel defenders mined a massive refinery complex, the detonation of which by the Imperial invaders resulted in a blaze that put out enough carcinogenic smoke and soot that the entire area was covered in deadly murk. Unprotected humans had to wear full-body protection gear as a result. The fall of the citadel was said to resemble a city made into a bonfire, lighting a sky darker than Old Night itself. The initial force sent to claim Boeotia was made up solely of Imperial Army forces, of which the Tupelov Lancers are the only regiment known to have actually been present, under the leadership of a Commander Selud. After six weeks and the loss of the refinery fields - both seen as critical errors - Selud was removed from command and control of the campaign assigned to the Thousand Sons Legiones Astartes for a quick finish.
Up until the Thousand Sons took control of the theatre, a conservator team led by Kasper Hawser and Navid Murza operated in the area during the campaign, exploring and recording the contents of an ancient shrine to the gods of a more superstitious age. The shrine had been uncovered by a wayward artillery strike, and the decision made to catalogue the contents at once; conservator teams had been assigned to the Army's tail, along with iterators, engineers, aid workers and other groupings designed to ease Boeotia swiftly into the Imperial fold once it had been successfully annexed. Hawser's team was ultimately ejected before their analysis could be completed, despite their Unification Council credentials, by warriors of the Fifteenth Legion. Sixteen months after the Boeotian Conflict was ended, conservator teams were finally allowed back into the region. No trace of the shrine could be found.