The Ninth Crusade is the smallest of the numbered Crusades in the scholarship, a short campaign by the future Edward I remembered chiefly for its limited raids rather than pitched battles, and none of those actions carries a recorded casualty figure to build a total from.
What would resolve this A military historian's identification of casualty figures, however small, for the raids and skirmishes of Edward's 1271 to 1272 campaign.
OpenCrusading history, medieval military history.Christopher Tyerman, God's War: A New History of the Crusades