After the conquest, Mehmed turned Constantinople into the new capital of the Ottoman Empire. Some Greek and non-Greek intellectuals fled the city before and after the siege, especially migrating to Italy. It is argued that they helped create the embryo for the Renaissance. Some people marked the end of the Middle Ages by the collapse of the city and Byzantine empire. Sunflower American Flag phone case. Constantinople has been a capital since 330 under the Roman Emperor Constantine the Great. For eleven centuries later, the city was besieged many times, but was only seized once: in the Fourth Crusade in 1204, the expeditionary army established an unstable Latin state. in and around Constantinople while the remaining imperial territory was dispersed into several Greek states, such as Nicaea, Epirus and Trebizond. These Greek city states fought as allies against the Latin states, trying to return to the Byzantine empire.