As noted here , the majority of the imperial forces doesn't know exactly where they're fighting. In addition, not even the higher-ups of the sectors that give their tithes to the war effort seem to know exactly where they're spent, instead thinking they're still funding the Margin Crusade.
Why is this a masterpiece of deception and outgame genius storywriting?
Why is this a load of crap and doomed to fail anyway?
I just prefer it when it's all just a tiny bit more small scale, recovering artifacts, bodyguarding an inquisitor when he makes first contact with a race of xenos, etc.).