Aaron Dembski Bowden, one of the best of Black Library has to offer. A level 1 writer according to G-Canon. And here's his short on the celebration. Not just some random story in 40K universe but one that makes sense. 

WHY?

    Because Aaron is supposed to write the crimson fists novel Rynn's World but  Steve Parker(G-Canon Level 3) beat him to it. And Rynn's World turned out to be disappointing and shitty book. If I had a chance to visit any part of 40K universe I wouldn't visit Rynn's Worlds. I wish ADB wrote that book but always remember, "YES!, the truth hurts".

So ADB returns with a short story for the celebration : FOR THE FALLEN

  
 
THE SHORT
 
     We return to the ruins of the Rynn's World and have some drama moments. I want more Crimson Fist novels written by ADB. But that's the best we get so far. 

THE FAILURE

Spoiler's about Rynn's World: Space Marines don't listen to orders, a random rocket blow the whole fortress of Crimson Fists and they all died, you get to read walking scenes with Crimson Fists and an old lady and her kids for 40 pages. And when they arrive at the capital city nothing important happens just more boring pages to be read. The whole book is just a waste of time. I wont read stuff by Steve Parker if he wrote anything else.

THE EXPECTATIONS AND MORE FAILURE

    Pedro Kantor has a cool model, and crimson fists are supposed to be an important chapter, but thanks to Rynn's failure and Matt Ward's general "ALL CODEX MARINES ARE ULTRAMARINES" approach on the codex space marine. We don't have a good concept of Crimson Fists, just paint them blue and paint the hands red there you go, Crimson Ultramarines(fists not included in the box).

Ward-Rage never gets old.