What does O'Brien mean when he writes, “they were too frightened to be cowards?" Why does he use this contradictory statement to describe feelings of the soldiers?

O'Brien uses the theme of carrying in his text resulting in a comprehensive criticism of this idea. In his text, he shows the different types of luggage's men carried. However, O'Brien tries to show their humanity in the way they are careful in carrying the things they have from their loved ones, like letters