 Complete the following phrase:  The main narrative picks up with the Barons Crusade under King Theobald I of Navarre gathering at Marseille in 1239. This section, which is vivid and detailed, is interrupted at one point for an excursus on the names of Babylon. One chapter 27 is devoted to the Ayyubid Egyptian intelligence system. Two chapters 3031 are poems written by discouraged crusaders, one written by a nobleman in captivity. The expedition of Earl Richard of Cornwall is covered in less detail than that of the king of Navarre chapter 36. Two chapters 4041 cover the Khwarazmian 