The Byzantine empire was where the eastern empire of Rome used to be, with its capital being Constantinople.
Alexios I Comnenos, Constantinople
They used the situation to weaken their greatest commercial competitor, the Byzantine Empire.
Holy Roman Empire, England, and The Byzantine Empire
Alexios I Komnenos was the Emperor of the Byzantine Empire during the First Crusade, which occurred largely as a result of his appeals to Western Christendom for help against the tide of Islam.
The Byzantine Empire did not recover from the fall of Constantinople to the Turks because the Turks were a strong local power which captured all of the remaining byzantine territory. Whereas the 4th Crusaders were few in number after they divided up the empire and they only captured part of the Byzantine Empire, the remainder of the Empire split into independent Byzantine powers, one of which the Empire of Nicaea eventually recaptured Constantinople and restored the Byzantine Empire.
In the fourth crusade the Christian Byzantine Empire was attacked by Italian sailors (the Venetians). It was not a true crusade; no Muslim powers were attacked.
Saw an opportunity to neutralize the Byzantine empire and diverted their army to Constantinople.
Saw an opportunity to neutralize the Byzantine empire and diverted their army to Constantinople.
The city of Constantinople, the capital of the Byzantine Empire, was sacked and partially destroyed by the armies of the Fourth Crusade in 1204. This attack on fellow Christians caused a centuries-long schism in the church and allowed the Turks to conquer parts of the Byzantine Empire.
There was no advantage of the fourth crusade. The Venetian just randomly attacked the Byzantine and brought a fellow Christan empire to it's knees and sacked the city.
During the Byzantine Empire.
The Capital of the Byzantine Empire was originally called Byzantium before being renamed as Constantinople (which was its name during its control by the Byzantine Empire) and renamed by Ottomans as Istanbul afterwards. Constantinople was the capital of the Byzantine empire