My son has difficulty reading and even more difficulty finding books he likes. Often those two things go hand in hand. He wants to find high-interest novels that take place in the middle ages.

He does not like fantasy or science fiction, and was the only one of my kids to dislike Magic Tree House when he was younger and Harry Potter when he was older.

Do you know of any titles that are appropriate for 4th or 5th grade reading level?

The Knights of Arrethtrae series is excellent and my son loves them. Unfortunately none are available on PBS right, all are WL.

The Lantern Bearers and The Shining Company - Rosemary Sutcliff - she writes some great YA historical fiction set in medieval times

The Squire's Tale by Gerald Morris

He might like If You Lived in The Days of the Knights by McGovern also.

I'm guessing he likes historical fiction. I coach Battle of the Books and the one book I remember the boys enjoying the most is Blood On The River by Carbone. It is historical fiction/adventure set in 1607 Jamestown.

Midnight Magic by Avi was reasonably good.  It's the right time period, but it does have a hint of the magic/fantasy.  I still think it might be a good fit here.

There is an older book called Brother Dusty-Feet that might work...however it's wishlisted here and may be a little more difficult to locate.

To the Edge of the World might entertain him, but again it's going to be a bit more difficult to find (currently there is no wishlist for this one).

Other than that the only thing I can think of is to perhaps pick up some books from other areas of history that complement what he likes and see if you can get him to branch out a bit.  Perhaps something like Brian Boru or The Vikings by Morgan Llywelyn might work (The Vikings reads a bit more like a non-fiction book...lots of facts and not a complete comprehensive story).

My other thought, one which you may or may not like is to perhaps look around and see if you can find some non-fiction books based in the renaissance for him.  Honestly, from the way you describe him, it sounds like he may be the type of child that is far more content with non-fiction.  It sounds like he may enjoy books where he feels that he is actually learning something rather than reading a story (often kids who like knights and kings but not fantasy are like this).  If you find this to be the case you might want to invest in some Osprey books.

Let me know if you need more ideas.  I have several friends that are renaissace reinactors with kids that would have more books laying around in this area that I haven't yet gotten ahold of.

I asked my friend who is a children's librarian as well as a renaissance reinactor.  This is what she had to say:

"I would recommend the Ranger Apprentice series but they are fantasy and a bit on the hard side for 5th grade. Excellent books with thinly veiled geographics to real peoples and times. But still fantasy. There are some older titles that aren't fantasy at lest by the usual standard. The Striped Ships that might work. Robin Hood. King Arthur and his Knights of the Round Table. The Sword in the Tree. The Door in the wall. Pearl in the Egg. The Knight at the Squire. King Arthur's Page. Arrow over the door."