Translation:Terrible things are experienced in war.
Is "fearsome" just too far, too distinct, from "dreadful" to be accepted? I tend to take "fearsome", "frightful", and "dreadful" as equivalent, though "dreadful" is most commonly used in my experience of English.
Vikings were fearsome warriors. I wouldn't have wanted to be the one telling vikings that they were "dreadful" warriors. ;0)
Fearsome (describes the appearance of something fear-provoking, intimidating, formidable) and "frightful" (full of fright, a feeling of dread, an extreme negative reaction) could be considered opposite sides of the same coin.
A great translation for fearsome is fryktinngytende. Awesome word; I love the sound of it. :0)