Son in all seriousness, the reason why it's Orks specifically is because there are prominent mentions of campaigns in the Great Crusade against major Ork empires, some of which were able to fight the fledgling Imperium on pretty equal terms. (Including that one Warboss who looked at the Emperor and said to himself "I'm about to choke a bitch".) Ullanor is one, but there's a few mentioned, with quite detailed mentions going back to before the Horus Heresy series. Many of these Ork empires had large populations of human slaves who they forced to produce munitions for them - an atrocity mentioned frequently in the histories of the Imperium, which of course would would never use forced labour to produce its munitions.
So if we view the galaxy post Age of Strife as kind of a like house of cards - lots of worlds that had been isolated and could be conquered pretty quickly by any aggressive power with a big fleet - then "some big Ork empire" is not a terrible bet for who would be knocking them down, if the Emperor hadn't done it first. Indeed, a lot of the crazy urgency with which the Great Crusade was conducted almost looks like a speedrun attempt at the galaxy. The Emperor seems to have been cognisant of the fact that he had a limited window to act in, or his job would get a lot harder because there'd be less soft targets. Either because someone else had conquered them first, or they had formed
alliances against roving conquerors.
The second most popular candidate for this is the Rangdan, who have achieved memetic status as "big scary alien empire who could fight the Imperium on equal terms", let down by the fact that they only show up for like a page in one book. The Orks have had a lot more detail for much longer, often being one of the only detailed depictions of who the Imperium were fighting during the Crusade. Plus recently they had a
twelve novel series where they were the major antagonists, which has a lot of extremely stupid stuff in it.
Obviously this is taking a view of 40K as a setting where other species or polities actually have agency, and history is a product of structural forces, rather than a story revolving around big men with bigger pauldrons. This is not necessarily the default read of the setting, to put it mildly, but if you are emotionally invested in 40K due to exposure at a vulnerable age, you quickly realise that you have to do a lot of the worldbuilding yourself if you want worldbuilding, rather than a crazy collage of different influences. Games Workshop certainly aren't going to do it for you, they're too busy sending death squads to fan animators.
Anyway, wasn't this meant to be a thread about sending boxes to 40K, not the Great Crusade?
