Susan Shwartz 
Cross and Crescent [EPUB ebook] 

The center of the greatest empire in the world, the seat of Christianity, Byzantium is a revered city. Marked by gargantuan monuments to God and peopled by the most royal of princes, and the most affluent citizens, Byzantium cannot possibly ever fall. Now under siege by Islam, the Byzantine Empire must look to Christians from the West for help in winning back Jerusalem, the most hallowed of cities. The Byzantines must prevent the disintegration of their empire while protecting the faith of many, but at what expense?