How could the crusaders, having failed to hold Jerusalem in 1187, were able to capture Constantinople in 1204?

Jerusalem was lost by local “decayed” crusaders in the struggle against the growing Muslims. Constantinople was captured by the new French and Venetians, taking advantage of the strife among the Byzantines.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.