Corsairs interfere with Imperial plans

While the Imperium continued the war on Mordecai against chaos, several Aeldari farseer's determined that the ongoing expeditions in the Hadron Expanse, especially those led by the Adeptus Mechanicus, were a danger to the plans of the eldar. The Imperium had not given up on Hexis, and now looked likely to reinforce their positions there following the opening up of the Rifts of Hecate. This risked the humans uncovering several ancient Necron artefacts, as well as Aeldari knowledge the xenos race decided the Mon-Keigh should not have.

To disguise their intent, the eldar employed raiding corsairs in the Hadron Expanse. Over the course of 11.021M42 the corsairs conducted a number of raids on imperial outposts, which resulted in the Ecclesiarchy worrying about the faith of the imperial citizens in the region. Acting swiftly, the state religion of the Imperium of Mankind deployed a number of Adeptus Sororitas units to key outposts, bolstering the faith of the people by their visible presence, while also acting as a shield against eldar aggression. In late 11.021M42 the two sides finally came to blows when the corsairs launched a raid against the seat of imperial power in the region - Vanir.

The corsairs were taken by surprise by the appearance of the Sisters of Battle, and had to fight with skill and intelligence to outmatch the ferocious assault led by the female human warriors. The raid itself had been a success, but now the eldar risked being cut off from their webway portal and trapped. This fact meant the xenos had to fight hard and not give ground, resulting in heavy casualties and an extremely close battle. Though they did not know it the Sisters came within touching distance of the portal, before finally the corsairs were able to force the imperial force to retreat. Battered, the eldar force managed to withdraw, and the eldar suspended raiding operations for the time being.