Hilaire Belloc, one of the most prolific Catholic authors of his time, gives a common sense explanation of why the Crusades were necessary, and why they ultimately failed. Belloc argues that the personal, and strategic, failings of the First Crusade’s leaders led to the establishment of a state that could not be sustained, and that the absence of such a state left Europe vulnerable to Muslim aggression for centuries afterward. Writing after the fall of the Ottoman Empire, shortly before World War II, Belloc believed that the tide had turned, and that the West had finally gained the advantage over its mortal foe. However, he also includes a prophetic warning to Western civilization about the eventual resurgence of Islam and its enduring desire to destroy Christendom.