What was Constantinople's rule in the crusades?

Constantinople played a crucial role in the Crusades as a key Christian city and the capital of the Byzantine Empire. It served as a major staging ground for Crusader armies, providing logistical support and resources necessary for their campaigns in the Holy Land. The city also acted as a cultural and religious link between Western Europe and the Eastern Orthodox Church, influencing the Crusaders' motivations and alliances. However, tensions often arose between the Byzantines and the Crusaders, culminating in events like the Fourth Crusade, which led to the sack of Constantinople in 1204.