 Complete the following phrase:  His reign saw considerable recovery of Byzantine power, including the enlargement of the Byzantine army and navy. It would also include the reconstruction of the city of Constantinople, and the increase of its population. He reestablished the University of Constantinople, which led to what is regarded as the Palaiologan Renaissance between the 13th and 15th centuries. It was also at this time that the focus of the Byzantine military shifted to the Balkans, against the Bulgarians, leaving the Anatolian frontier neglected. His successors could not compensate for this inadequacy, and both the Arsenite schism and two civil wars cf. 