While the first three Crusades were launched in an effort to reclaim Jerusalem from Muslims, the Fourth Crusade, begun in 1202, pitted Christians against Christians: Roman Catholics against Orthodox.
Real Crusades History on MSN

Why Did the Fourth Crusade Really Happen

Launched by Pope Innocent III to reclaim Jerusalem, the Fourth Crusade instead ended up sacking the Christian city of Constantinople due to debts, Venetian trade‑games and Byzantine intrigue.
The International History Review is the only English-language quarterly devoted entirely to the history of international relations. An international journal on international history, the Review ...