I am going back to the start of the Horus Heresy books. It has been a long time since I read them.
I thought the first book covered the events at Ullnor, the moment the Emperor announced he was returning to Terra and was going to name one of his sons war master. I remember a scene where Malcador tells Horus ahead of time he will be chosen.
However having got into book 1 it is clear this picks up a year after this happened and I don't seem to have come across this scene yet.
Which of the early Horus Heresy books covers these events first in detail? (I know various books and stories cover the same events from different perspectives throughout the series).