In 1394, Bayezid laid siege(long blockade) to Constantinople, the capital of the Byzantine Empire. Anadoluhisarı fortress was built between 1393 and 1394 as part of preparations for the second Ottoman siege of Constantinople, which took place in 1395. Already in 1391, the rapid Ottoman conquests in the Balkans had cut off the city from its hinterland. After constructing the fortress of Anadoluhisarı to control the Bosporus strait, from 1394 on, Bayezid tried to starve the city into submission by blockading it both by land and, less effectively, by sea. Lack of a fleet or necessary artillery to demolish those impressive walls made this an abortive siege. These lessons would later help the later Ottoman emperors. On the urgings of the Byzantine emperor Manuel II Palaeologus, a new crusade was organized to defeat him.