Some books are a chore to read, even if the subject interests you, but a necessary chore. Like textbooks when you’re in school. For me, Philip Line’s The Vikings and Their Enemies: Warfare in Northern Europe, 750-1100 was that kind of book. It contained information I needed and from which I profited, but I thought it would never end.
Casual readers will probably find it long and daunting, as the Amazon reviews indicate. First of all, though “Vikings” is in the title, that word here indicates the time period, not the main subject. Most of the material does not focus on the Vikings themselves. The main reason for this is that the author, like so many historians, is skeptical about the Icelandic sagas as sources, and so uses them only lightly. That leaves him with limited source materials about Scandinavians. Most of the ink is devoted to the Vikings’ enemies, the British, the Irish, the French, the Germans, and a few others. For them we have a certain amount of documentary evidence (though Line handles that evidence with caution too).
The practical upshot is that he spends a lot of time telling us that popular histories are wrong about many, many things that have entered the general information pool. Which is the mark of a rigorous historian. But it does not make for an exciting narrative.
However, the book contained, in particular, some information on Viking naval tactics that I needed for the book I am writing. So the work I put in reading The Vikings and Their Enemies was well worth it to me.
The normal reader will probably find other books on the period more interesting and easier to consume. I recommend this one only for its appropriate audience.