User blog comment:CaptainAndrath/Alternate Heresy/@comment-24.147.176.60-20131102232321

Kurze had his issues but he never lost it. Even at the end he was sane. Kurze is really the opposite of Sanguinius. Both had visions their entire lives and both had predicted their own deaths. I could make arguments for both Angron and Perturabo but I think Lorgar would have been the one no matter what. Since the Emperor failed to understand what it meant to be less than himself as evidenced by the conversation on Terra with the priest of the last church; the Emperor would not have understood what his actions on Khur meant to someone like Lorgar and his legion and his people. Lorgar was the one primarch truly doomed by his circumstances and his father. Arguments could also be made for Magnus with regards to Tzeentch's plans for him but there isn't quite enough evidence that I could argue it fully.

All that said I can think of arguments for every well known primarch with the exepction being Jaghtai Khan and Corrax since those are the two I know least; that any of them could have started the fall to chaos. They all had their own reasons and triggers. In the end the only true person that could be argured at fault is the Emperor himself. In his arrogance he assumed he was right and look at how that played out.