The Sixth Crusade is remembered as a diplomatic success, Jerusalem recovered by treaty rather than conquest, and the scholarship reflects that emphasis: the campaign's limited fighting is described in narrative terms with no casualty figures attached, let alone a combined total.
What would resolve this A military historian's accounting of the skirmishes and garrison actions that did occur during Frederick II's campaign, however small the resulting figure.
OpenCrusading history, medieval military history.Christopher Tyerman, God's War: A New History of the Crusades