Lambert has written a great book to explain the difference between crusaders
and jihadists, and, in particular, to explain that, from the beginning, the
history of Islam should include its internal divisions.
The first few chapters are a short history of the rise of Islam with notes about the situation in Christian Europe. Then, after the destruction of the Holy Sepulchre, Lambert turns to the chaotic state of the Papacy and shows how Urban II reached the point of calling for the Crusade. Then we get a detailed description of the route and the battles of the first Crusade. Then he describes life in the crusader states. Then how Saladin rose to power and defeated the crusaders, with the important footnote that his boss Nur al-Din, who inspired Saladin, was actually mainly targeting not "infidels" but Shiites, who in theory were fellow Muslims. In fact, until 1187 Saladin conquered land from Muslim kingdoms, not Christian ones.
Lambert continues the story alternating between Christian Europe and the Islamic kingdoms (in Spain, Egypt and Turkey) and continues way past the Crusades, well into the 16th century of Suleiman. The last two chapters bridge the story of the Middle Ages and the modern times.