Irisian War

The Irsian War was an Imperial xenocidal excoriation campaign carried out by the Storm Sentinels Space Marine Chapter against invading Orks that were besieging the Imperial world of Iris Prime. Despite their lack of formal weapon training, the Irisians volunteer to fight alongside their Astartes saviours, and ruthlessly and valiantly fight against the Greenskins. In recognition of their valour, the Storm Sentinels Force Commander convinces the Imperium to build a new Astra Militarum base in order to recruit such a hardy and valorous stock for the Imperium's fighting forces.

History
In 774.M40, a large force of invading Feral Orks invade the Imperial world of Iris Prime and begin to sack the planet's settlements. Sending out a desperate Astropathic distress signal, their prayers are answered in the form of the Storm Sentinels Chapter. A Strike Force is immediately dispatch to the planet to deal with the threat. The residents of Iris Prime volunteer to fight the Ork hordes and are given las weaponry, even though many of the Irisians didn't have any formal weapon training, they are able to hold their own against the Orks. The combined might of the Chapter Strike Force and the Irisian citizens are able to quell the Orks. The Force Commander is impressed by the Irisian's skill in combat and requests that an Astra Militarum base be built on the planet for the citizens' combat prowess to not be wasted.