Never knew Steinbeck tackled King Arthur but I immediately grabbed it when I saw it in the Little Free Library I sometimes frequent. His lefty ass might give an interesting take on the mythos that have never really appealed to me but maybe in this form they will.
TH White's version (The Once and Future King) is a pacifist reading of Arthur with emphasis on how a nation can be stably governed. It's well worth a read. It starts with The Sword in the Stone, which is relatively light-hearted, but gets more serious as it progresses.
Ben! (Boo!)
Donald Hobern