I'm wondering, as I'm fuzzy on one little detail, I'm familar with the Horus Heresy and find it a fascinating subject. Here's my question, why did the Emperor teleport onto the Vengeful Spirit? Was he aware that reinforcements were on the way? I mean most sources I read on the Horus Heresy makes it seem that victory was inevitable for the loyalists because Horus wasted too much time. If the Emperor was gonna win by default, why risk everything in such a daring assault?
Was he aware the Ultramarines were arriving with reinforcements or did he not know?