The Fourth Crusade is originally designed to conquer Muslim Jerusalem by means of an invasion through Egypt.
Instead, in April 1204, the Crusaders of Western Europe, in collusion and with the backing of Venice, invade and conquer the Christian (Eastern Orthodox) city of Constantinople, capital of the Byzantine Empire.
This is seen as one of the final acts in the Great Schism between the Eastern Orthodox Church and Roman Catholic Church.
It has been often described as one of the most profitable and disgraceful sacks of a city in history.
