Yet.. Sanguinius was the one who delivered the blow that caused the Emperor to be able to even defeat Horus in the first place.... Oh.. and he happened to be there with his legion, not on teh otehr side of the universe.
Considering how far away the Ultramarines were from Terra they only got to Earth very shortly after the DA & SW who were much, much closer. The Blood Angels were, relatively speaking, very close to Terra, so that would be like saying you're in Texas and I'm in Toronto lets see who can get to the Alamo (spelling?) first and if I can't get there at the same time as you I'm obviously crap.
The fact was, Guilliman was the Lord Commander of the Imperium, so it was most definitely him who ordered the Navy to fire on the Imperial Fists.
He was a Lord Commander but that doesn't mean he ordered that ship to fire on the Imperial Fists, he declared Dorn a heretic (and for all we know that just might have been a fit of anger breaking through his aloof facade) yet if he'd commanded the Imperial Navy to fire on the IF you'd think it would be mentioned somewhere. More likely was the fact that a number of Imperial Navy Commanders took it upon themselves to persecute the Sons of Dorn because they believed it was what Guilliman wanted (it's happened before in English history so why not in 40k?).
And thats Corax, 'Oh I'll just mutate my chapters geneseed and create a bunch of mutants I'll have to euthanise', and Khan 'I'll hide at the back in this Razorback while you guys fight out there' who supported him?
Don't you mean Khan 'I helped save Terra by throwing myself directly at the traitors rather than hiding behind the walls of the Palace like Dorn and Sanguinius?
', whereas Dorn 'I was too blinded by rage to even bother trying to save the Imperium
' was supported by Russ 'I have an entire legion of undisciplined, mutant Astartes
' and Vulkan 'well I have a tiny legion so the Codex won't really effect me but I like being argumentative
And having 70 -90% of your chapter destory, just defending not being in battle against any tough opponants, after the Heresy... thats really bad leadership in anyones books.
Not any tough battles, you know except for all those tough battles against every Xenos race that attacked the Imperium at it's weakest moment, all those Traitors that need to be driven out of the Imperium...yeah those battles were so easy. Unlike the other Legions they didn't stay concentrated they spread through out the enitre Imperium holding it together, the fact that all the Ultramarines weren't slain speaks of a genius level of leadership at work.
The fact is, the Smurfs aren't very good at anything and got everything they did by sheer luck rather then battling for it.
They are/were one of the most disciplined, tactically flexible Chapters/Legions of their time- unlike the berserkers of the Blood Angels or the intrinsically undisciplined Space Wolves the UM work as a proper military force.