For a start, ignore any Hollywood-esque nonsense.
In fact ignore stories about Arthur, Lancelot, Holy Grials and the like.
King Arthur is a work of fiction.
There has never been a King Arthur since Norman times (late-11th Century); and no known, English, King Arthur from the Saxon era the Normans replaced.
Even if there had been a Saxon king, when England was coalescing from several kingdoms, who might have inspired the story, he and his militia would not have looked anything like the characters in your illustration. That shows Mediaeval practice, contemporary with the Arthur story's original publication.
The Arthurian legends were invented in the 15th Century by the English writer. Sir Thomas Malory, in one of the first known novels. Even the writer Malory's identity is vague because there are several Thoman Malorys identified in the official records of the time!
Malory drew on older French sources for inspiration, and subsequently the French writer Chrétien de Troyes added Lancelot and the Holy Grail to the stories.
So if you want to study the Saxon era seriously and credibly, don't use a Mediaeval Norman novel as a source!
