Maiden Rose, or Hyakujitsu no Bara, is a popular mature-rated title about a commander and his "knight" who try to make a relationship work in the midst of a harsh war. It was made into an anime OVA back in May this year; the OVA is still unlicensed. (Hint, hint, Media Blasters!) Here, have a trailer.
One of the reasons why Maiden Rose is so popular is that while one of the characters is very effeminate, not ALL of them are-- you'll see very quickly that one of the men in ths relationship is decidedly...well, manly. Which is pretty unusual in your average yaoi! It's also got phenomenal art and an interesting story, so how can you get better'n that?