" From the seventh to the tenth centuries, Muslims conquered “fully two-thirds of the Christian world.”8 Not until the eleventh century did Europe finally respond. So it was hundreds of years of unrelenting violence and persecution by Islamic armies that sparked the Crusades. Thomas F. Madden, among the world’s foremost authorities on the Crusades, explains, “The crusades were in every way a defensive war.”9 Today, there are many—even in the Western media—who perpetrate the notion that the Crusades were an unprovoked, imperialistic attack upon peaceful Muslims. "

― Erwin W. Lutzer , The Cross in the Shadow of the Crescent: An Informed Response to Islam’s War with Christianity