In 40K News: Bill King, Writing about the Macharian Crusade

[Bob the Gunslinger]

No, they're horns, just like on the model; they're a reference to Alexander the Great, who was often depicted as a sort of demigod, as represented by his having horns.

Did you even look at the model?

[The Reaper]

I heard the Macharian Crusade was similar to what they thought would happen at the end of the Great Crusade. They tore up the worlds in their path, but they reached the Halo Stars and it is said that Macharius wept when he knew that he couldn't go any further, after that everyone got bored and, not having anything to do, they turn on eachother. It is also said Macharius disappeared (he might be being kept by Trazyn.)

[madd0ct0r]

So the picture is not to be taken literally?

Because that's all the trappings of a classic living saint there, and I really didn't think he was one, just a good general.

[Optimus Metallus]

Yeah, taking a closer look at the picture, those are laurels and not horns. Sounds like it'll make for a really great book, though. Macharius has always been one of my favorite characters from the 2nd edition Codex: Imperial Guard.