Another great Ultramarines novel is 'Ultramarines: The Chapter's Due' by Graham McNeill. This novel showcases the Ultramarines' relationship with other factions in the Warhammer 40,000 universe. It also explores their code of honor and how they deal with challenges that test their principles. It's full of intense battles and political intrigue within the setting.
There might also be some veteran Ultramarines who have seen many battles and act as mentors to the younger ones. These characters can bring a lot of wisdom and experience to the story. Their stories of past battles can inspire the younger Ultramarines to show even more courage in the face of danger. And of course, they are also role models for honor within the chapter.
Well, in some 'courage and honor ultramarines fanfic', there could be plots about the Ultramarines facing extremely tough alien races. For example, they might engage in a battle where they are outnumbered but still show great courage. Their sense of honor drives them not to retreat easily.
Sure. 'Know No Fear' is a great start. It's easy to follow and gives a good introduction to the Ultramarines. You'll get to know their basic values and how they operate in combat situations.