Byzantine Empire (13th – 15th c.)
The Fourth Crusade turned against the Byzantine Empire in 1204 and the Crusaders conquered about one half of the Byzantine territory relatively fast: Thrace, Macedonia, part of Thessaly, Peloponnesus, Aegean and Ionian islands, Crete and several cities in western Asia Minor. The lands conquered by the Crusaders became the basis for the creation of the Latin Empire in 1204 which was divided into vassal fiefs: the Kingdom of Thessalonica, the Principality of Achaea, the Duchy of Athens, the Duchy of the Archipelago and the short-lived duchies of Nicaea, Philippopolis and Philadelphia.
Baldwin IX Count of Flanders who was crowned Latin Emperor as Baldwin I had direct control only over part of Constantinople, part of Thrace, northwestern Asia Minor and few Aegean islands. Thus the power of the Latin Emperor was limited already from the start because all important newly established duchies in central and southern Greece were subordinated to the leader of the Fourth Crusade, Boniface of Montferrat. The Latin Empire was further weakened by the rebellions of the local population, while the Byzantine nobility founded the Empire of Nicaea in Asia Minor as a Byzantine successor state under Theodore I Lascaris, son-in-law of Emperor Alexius III Angelos.
Byzantine succession was also claimed by other states including the Despotate of Epirus and the Empire of Trebizond but the Empire of Nicaea had the leading role in the revival of the Byzantine Empire. Nicaea gradually extended its territory on the expense of the Latin Empire until Michael VIII Palaeologus or Palaiologos (Nicaean emperor from 1259) finally recaptured Constantinople in 1261. The Byzantine Empire was revived under the Palaeologan dynasty which ruled the Byzantine Empire until the fall of Constantinople in 1453.
Michael VIII Palaeologus was after his death in 1282 succeeded by his son Andronicus II Palaeologus (1282-1328). The Byzantine Empire declined to the status of a minor state and became seriously endangered by the Ottoman Turks in Asia Minor and Serbs in the Balkans. Exclusion of his grandson, the future Andronicus III Palaeologus (1328-1341) from the succession provoked a civil war which ended with the Emperor’s deposition. Andronicus III Palaeologus failed to restore the former glory of the Byzantine Empire as well, while a civil war (1342-1347) that broke out for the regency to his nine-year old successor John V Palaeologus (1341-1391) severely weakened the central authority.
John V became sole-emperor in 1354 but imperial power continued to decline. The Ottomans continued territorial expansion on the Byzantine expense and John V was forced to recognize Ottoman suzerainty in 1371. He was deposed by his eldest son Andronicus IV Palaeologus in 1376 but Sultan Murad I helped him to regain the throne. In 1390, John V ordered strengthening of the Constantinople Golden Gate but Murad’s successor Sultan Bayezid I forced him to abolish his works.
John V Palaeologus was succeeded by his second son Manuel II Palaeologus (1391-1425), while his younger son Theodore I Palaeologus inherited the Despotate of Morea in 1381. Sultan Bayezid I laid a siege to Constantinople shortly after Manuel’s accession to the Byzantine throne but Manuel II managed to conclude a peace treaty with Bayezid’s successor Mehmed I in 1403. The Ottomans laid another siege to Constantinople in 1422 and conquered southern Greece one year later. Manuel II and his son and heir John VIII Palaeologus (1425-1448) were forced to sign an unfavorable peace treaty in 1424 and pay tribute to the Ottoman Sultan.
John VII Palaeologus became sole-emperor after his father’s death in 1425 but his empire encompassed only Constantinople and its surrounding area. He appealed to the Western states for help against the Ottomans and offered unification of the Greek and Roman Churches after the fall of Thessaloniki in 1430. However, military assistance from the West never arrived, while proposed union between Eastern and Western Churches disturbed the Byzantines. John VIII was succeeded by his brother Constantine XI (1448-1453) who was killed during the Fall of Constantinople on May 29 in 1453 when the Ottoman forces captured the city and the Byzantine Empire finally collapsed.