Ximoro'An has a long history of engaging the Astartes or Space Marines of the Imperium. On every battlefield that they appear against the Tau forces that O'An is a part of he makes it his top priority to exterminate them and has grown increasingly good at it. The lives of many a Space Marine officer have been taken by O'An himself and he is known for making use of one of the most dangerous and close ranged battlesuite configurations aswell as his use of very assault oriented tactics some Shas'O have critisized him for being overly agressive but his results cannot be ignored. The exact reasons for these tendencies and the details of his past are unknown as he refuses to speak about them. Por'hui broadcasters have tried delving into his past records but have found nothing extraordinary apart from the usual record of battles and advancement through rank though there are some gaps in the records most notably between the time of the Arkunasha war and the Damocles Gulf Crusade. Despite these coincidental gaps more in depth investigation was deemed to be against the greater good and abandoned for the time being. It is however theorized that he served under O'Shovah during the Arkunasha War and the Damocles Crusade and was among the troops that engaged the Space Marines outside of Gel'bryn on Dal'yth. The only record to support this was a passing report of the promotion and reassignment of a handful of Shas'vre immediately after the Imperials pulled out of Dal'yth. If O'An was one of those Shas'vre it raises a number of questions as to his agenda and his loyalty.

 

 

In recent years he participated in several operations during the Third Phase Expansion leading Tau forces on an as of yet un-named world known only as VR-15. He successfully lead the Fire Caste forces in pushing the Imperials off of the world including two companies of Space Marines that had tried to defend the mining facilities of the planet. Without the resources flowing from VR-115 Imperial forces in the immediate area were forced to retreat to another planet in the system VR-4. The campaign to take this planet is still continues. At first the Or'es Shi drove the Imperial forces back across the planet taking the entire eastern hemisphere. However the Or'es Shi was then recalled off the planet to other crisis areas in the system. Upon returning O'An was furious to see that the Tau forces had been ground to a halt in the dense jungles and underground ruins of the western hemisphere and had been pushed back to the eastern side of the planet. Currently the Aun in command has formed a truce with the Imperial forces but hostilities are expected to commence again. O'An however has been called to aid  in the fighting on Medusa V and hopes to finish the campaign on that planet before combat flares up again on VR-4.