 Complete the following phrase:  Before the beginning of the siege, Mehmed the Conqueror made an offer to Constantine XI. In exchange for the surrender of Constantinople, the emperors life would be spared and he would continue to rule in Mystra. Constantine refused this offer. Instead he led the defense of the city and took an active part in the fighting along the land walls. At the same time, he used his diplomatic skills to maintain the necessary unity between the Genovese, Venetian, and Byzantine troops. As 