The time of the Third Crusade, being the end of the 12th century, was a period of transitional armor. This extended to shields. While the Norman kite shield had been the shield of choice for a warrior for over a hundred years and the heater shield would become the shield of choice in roughly fifty years what would be most common for a knight during the Third Crusade?
Bonus for any period artwork from manuscripts, tapestries, or tombs that show a shield from that era.
It was an intermediary design, basically a long heater though some still had rounded tops. The Osprey Men-at-arms series has a lot of books dealing with the middle ages. I’m not sure what you mean by transition as that label is better used for the 14th century when maille and coat of plates started giving way to plate which would eventually dominate armour types for the rest of the middle ages.
Check this link for a book on it. Some of the pages from the book are shown and might be of some help.
http://www.amazon.com/Third-Crusade-1191-Lionheart-Jerusalem/dp/1841768685#reader_1841768685
Just scroll down once the page loads to see what’s there.
Comment by cernunnicnos — July 29, 2010 @ 9:37 pm