Although the Palaeologi emperors recaptured Constantinople from the Western Europeans in 1261, they were never able to regain control of much of the former imperial lands. They usually controlled only a small section of the Balkan Peninsula near Constantinople, the city itself, and some coastal lands on the Black Sea and around the Aegean Sea. The former Byzantine lands in the Balkans were divided between the new Kingdom of Serbia, the Second Bulgarian Empire and the city-state of Venice. The power of the Byzantine emperors was threatened by a new Turkish tribe, the Ottomans, who established themselves in Anatolia in the 13th century and steadily expanded throughout the 14th century. The Ottomans expanded into Europe, reducing Bulgaria to a vassal state by 1366 and taking over Serbia after its defeat at the Battle of Kosovo in 1389. Western Europeans rallied to the plight of the Christians in the Balkans and declared a new crusade in 1396; a great army was sent to the Balkans, where it was defeated at the Battle of Nicopolis. Constantinople was finally captured by the Ottomans in 1453.
Who was defeated at the Battle of Kosovo?
Serbia

The greatest mosaic work of the Palaeologan renaissance in art is the decoration of the Chora Church in Constantinople. Although the mosaics of the naos have not survived except three panels, the decoration of the exonarthex and the esonarthex constitute the most important full-scale mosaic cycle in Constantinople after the Hagia Sophia. They were executed around 1320 by the command of Theodore Metochites. The esonarthex has two fluted domes, specially created to provide the ideal setting for the mosaic images of the ancestors of Christ. The southern one is called the Dome of the Pantokrator while the northern one is the Dome of the Theotokos. The most important panel of the esonarthex depicts Theodore Metochites wearing a huge turban, offering the model of the church to Christ. The walls of both narthexes are decorated with mosaic cycles from the life of the Virgin and the life of Christ. These panels show the influence of the Italian trecento on Byzantine art especially the more natural settings, landscapes, figures.
The panels from naos show what influence on Byzantine art.
Italian trecento

In Rome, state cult to a living emperor acknowledged his rule as divinely approved and constitutional. As princeps (first citizen) he must respect traditional Republican mores; given virtually monarchic powers, he must restrain them. He was not a living divus but father of his country (pater patriae), its pontifex maximus (greatest priest) and at least notionally, its leading Republican. When he died, his ascent to heaven, or his descent to join the dii manes was decided by a vote in the Senate. As a divus, he could receive much the same honours as any other state deity libations of wine, garlands, incense, hymns and sacrificial oxen at games and festivals. What he did in return for these favours is unknown, but literary hints and the later adoption of divus as a title for Christian Saints suggest him as a heavenly intercessor. In Rome, official cult to a living emperor was directed to his genius; a small number refused this honour and there is no evidence of any emperor receiving more than that. In the crises leading up to the Dominate, Imperial titles and honours multiplied, reaching a peak under Diocletian. Emperors before him had attempted to guarantee traditional cults as the core of Roman identity and well-being; refusal of cult undermined the state and was treasonous.
As a living divus, what was the emperor to Rome?
father of his country