The passage above that begins with "Then rose the King and moved his host by night..." is actually from Alfred Lord Tennyson. It is from his _Idylls of the King: The Passing of Arthur_.

My usual territory is folk songs for Renaissance Festivals and the SCA, but I've been drawn to Tennyson since I was young. Just my 2p!

http://www.library.utoronto.ca/utel/rp/poems/tennyson55.html