World history, The Crusades?

Two books you may find helpful: _Chronicles of the Crusades_ by Geoffrey Villehardouin, Jean de Joinville and Sir Frank Marzials and _Arab Historians of the Crusades_ by Francesco Gabrieli. The first contains accounts of participants in several of the crusades including the fourth, which ended up taking Constantinople from the Byzantine emperor and didn't even get to the Holy Land. The second is a collection of excerpts from a number of contemporary Arab writers.