Fourth Crusade

The Fourth Crusade, from 1202 to 1204, was called by Pope Innocent III to recover Jerusalem by first striking at Egypt. Instead, through debt, diplomacy and opportunism, the crusading army attacked the Christian city of Zara on the Adriatic and then captured and sacked Constantinople, the capital of the Byzantine Empire. The crusaders and Venice divided much of the empire between them, and the sack deepened the rift between the Latin and Greek churches.

Innocent III proclaimed the crusade in 1198, and its leaders, mostly French and Flemish nobles, decided to travel by sea. In 1201 they agreed with the Republic of Venice to provide transport and supplies for 33,500 men for a year in return for 85,000 silver marks; Venice would also join with its own galleys for a share of the gains. But when the army assembled in Venice in 1202, only about a third of the expected number had arrived, because many had sailed from other ports, and the crusaders could not pay.

The elderly doge Enrico Dandolo proposed that the debt be postponed if the crusaders helped Venice recover Zara, today's Zadar in Croatia, which had rebelled and placed itself under the king of Hungary, himself a crusader. Despite the pope's prohibition and objections from some leaders, the army took Zara in November 1202. Innocent excommunicated the participants, later lifting the ban on the crusaders but not on the Venetians.

At Zara the leaders received a proposal from Alexios Angelos, son of the deposed Byzantine emperor Isaac II. If the crusaders restored his father, he promised money, troops for the crusade and the submission of the Greek church to Rome. The fleet reached Constantinople in June 1203 and attacked the city in July. The usurping emperor Alexios III fled, Isaac II was restored, and his son was crowned co-emperor as Alexios IV.

Alexios IV could not raise the promised money, and the population resented both the Latins and the taxes. Tensions grew through the autumn, and a great fire set during fighting destroyed much of the city. In early 1204 a palace official, Alexios Doukas, nicknamed Mourtzouphlos, overthrew and killed Alexios IV and took the throne as Alexios V. The crusaders, unpaid and with no prospect of supplies, resolved to take the city for themselves.

After a failed assault on 9 April, the crusaders broke through the sea walls on 12 April 1204. For three days they looted the city, killing many inhabitants, despoiling churches including Hagia Sophia and carrying off relics and treasures, many of which went to Venice; the bronze horses of Saint Mark's Basilica are the best-known example.

The victors elected Baldwin of Flanders as emperor of a new Latin Empire and divided the Byzantine lands. Venice took key ports and islands, including Crete. Byzantine successor states arose at Nicaea, in Epirus and at Trebizond. The army never went on to the Holy Land. In 1261 the Empire of Nicaea recaptured Constantinople, but the restored empire was much weaker, and the losses of 1204 contributed to its eventual fall to the Ottomans in 1453.

For Orthodox Christians the sack became a lasting grievance and helped make the East–West Schism permanent. In 2001 and 2004 Pope John Paul II expressed regret for it.

Our 1200 map shows the Byzantine Empire and Venice just before the crusade, and the 1279 map shows the restored Byzantine state after the recovery of Constantinople.