For eleven centuries the Byzantine Empire resisted a series of conflicts that lasted in and out of its territory. Although considered one of the strongest States in the Mediterranean, the empire had to face several conflicts that weakened its power over the time.
One of the factors that influenced was the Fourth Crusade, which ended up disintegrating its military forces. Ottoman invasions that occurred without success; and again in Constantinople (1453), this last one successfully, Constantinople was not able to resist the power of the invaders.