Where was byzantine empire in the crusades?

During the Crusades, the Byzantine Empire was a crucial player, particularly in the First Crusade (1096-1099). The empire, under Emperor AlexiOS I Komnenos, sought military assistance from the West to reclaim lost territories from the Seljuk Turks. However, as the Crusades progressed, relations between the Byzantine Empire and the Western Crusaders became strained, leading to tensions and conflicts, notably during the Fourth Crusade (1202-1204), which culminated in the sack of Constantinople in 1204, severely weakening the empire.