Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

I have heard of a few books that take place even before the first Horus Heresy book: Horus Rising.

Examples would be:
The First Heretic
The Last Church
The Primarchs

However, what I want to know is what is the first/earliest book of the Heresy timeline.