Crusades

===Fourth Crusade===
{{main|Fourth Crusade|Sack of Constantinople}}
[[File:ConquestOfConstantinopleByTheCrusadersIn1204.jpg|thumb|upright=1.35|[[Siege of Constantinople (1204)|Conquest]] of the [[Eastern Orthodox|Orthodox]] city of [[Constantinople]] by the Crusaders in 1204 (BNF [[Bibliothèque de l'Arsenal|Arsenal MS]] 5090, 15th century)|alt=Image of siege of Constantinople]]
[[File:LatinEmpire2.png|thumb|290px|alt=Multi-coloured map of [[Latin Empire|Latin]] and [[Byzantine Empire]]s|[[Latin Empire]] and Byzantine states in 1205. Green marks Venetian acquisitions; pink the Byzantine states; purple the Latin Empire and its vassals]]
In 1198, the recently elected Pope Innocent III announced a new crusade, organised by three Frenchmen: [[Theobald III, Count of Champagne|Theobald of Champagne]]; [[Louis I, Count of Blois|Louis of Blois]]; and [[Baldwin I, Latin Emperor|Baldwin of Flanders]]. After Theobald's premature death, the Italian [[Boniface I, Marquess of Montferrat|Boniface of Montferrat]] replaced him as the new commander of the campaign. They contracted with the [[Republic of Venice]] for the transportation of 30,000 crusaders at a cost of 85,000 marks. However, many chose other embarkation ports and only around 15,000 arrived in Venice. The [[Doge of Venice]] [[Enrico Dandolo]] proposed that Venice would be compensated with the profits of future conquests beginning with the [[Siege of Zara|seizure]] of the Christian city of [[Zadar|Zara]]. Pope Innocent III's role was ambivalent. He only condemned the attack when the siege started. He withdrew his legate to disassociate from the attack but seemed to have accepted it as inevitable. Historians question whether for him, the papal desire to salvage the crusade may have outweighed the moral consideration of shedding Christian blood.<ref>{{Harvnb|Jotischky|2004|p=168}}</ref> The crusade was joined by King [[Philip of Swabia]], who intended to use the Crusade to install his exiled brother-in-law, [[Alexios IV Angelos]], as Emperor. This required the overthrow of [[Alexios III Angelos]], the uncle of Alexios{{nbsp}}IV. Alexios IV offered the crusade 10,000 troops, 200,000 marks and the reunion of the Greek Church with Rome if they toppled his uncle [[Alexios III Angelos|Emperor Alexios III]].{{sfn|Tyerman|2019|pp=240–242}} When the crusade entered [[Siege of Constantinople (1203)|Constantinople]], Alexios{{nbsp}}III fled and was replaced by his nephew. The Greek resistance prompted Alexios{{nbsp}}IV to seek continued support from the crusade until he could fulfil his commitments. This ended with his murder in a violent anti-Latin revolt. The crusaders were without seaworthy ships, supplies or food. Their only escape route was through the city, taking by force what Alexios had promised and the new anti-westerner Byzantine ruler{{snd}}[[Alexios V Doukas]]{{snd}}denied them. The [[Sack of Constantinople (1204)|Sack of Constantinople]] involved three days of pillaging churches and killing much of the Greek Orthodox Christian populace. This sack was not unusual considering the violent military standards of the time, but contemporaries such as Innocent III and [[Ali ibn al-Athir]] saw it as an atrocity against centuries of classical and Christian civilisation.{{sfn|Tyerman|2019|pp=249–250}}