John V Palaiologos

John V Palaiologos or Palaeologus (, "Iōannēs Palaiologos"; 18 June 1332 – 16 February 1391) was Byzantine Emperor from 1341 to 1391.
Biography.
John V was the son of Emperor Andronikos III and his wife Anna, the daughter of Count Amadeus V of Savoy by his wife Maria of Brabant. His long reign was marked by the gradual dissolution of imperial power amid numerous civil wars and the continuing ascendancy of the Ottoman Turks.
Early rule and first civil war.
John V came to the throne at age eight. His reign began with an immediate civil war between his designated regent, his father's friend John VI Kantakouzenos, and a self-proclaimed council of regency composed of his mother Anna, the patriarch John XIV Kalekas, and the "megas doux" Alexios Apokaukos. During this civil war in 1343 Anna pawned the Byzantine crown jewels for 30,000 Venetian ducats. From 1346 to 1349, the Black Death devastated Constantinople.
Second civil war.
Victorious in 1347, John VI Kantakouzenos ruled as co-emperor until his son Matthew Kantakouzenos was attacked by John V in 1352, leading to a second civil war. John V asked the ruler of Serbia, Stefan Dušan for help, and Dušan obliged by sending 4,000 Serbian horsemen to his aid. Matthew Kantakouzenos asked his father for help, and 10,000 Ottoman Turks showed up at Demotika (Didymoteicho) in October 1352 and engaged the forces of John V's Serbian allies in an open field battle that resulted in the destruction of the allies and a victory for the more numerous Turks in the service of the Byzantines. The Ottoman Empire thus acquired its first European territory, at Çimpe and Gallipoli. Able to retake Constantinople in 1354, John V removed and tonsured John VI Kantakouzenos; by 1357, he had deposed Matthew as well, who had been captured by the Serbs and was ransomed to John V.
Rule and defeats.
In 1366, John V reached the Hungarian Kingdom, arriving at the Royal city of Buda to meet King Louis I of Hungary. However, the Byzantine emperor offended the king by staying on his horse, while Louis descended and approached him on foot. The Hungarian monarch then offered him help on the condition that John join the Catholic church, or at least achieve recognition by the Patriarch of the Pope's supremacy. The Emperor left the court of Buda with empty hands and continued his trip through Europe searching for assistance against the Ottomans.
The Ottomans, who had been allied with the Kantakouzenoi, continued to press John. Suleyman Paşa, the son of the Ottoman sultan, led their forces in Europe and was able to take Adrianople and Philippopolis and to exact tribute from the emperor. John V appealed to the West for help, proposing to Pope Urban V in 1367 to end the schism between the Byzantine and Latin churches by submitting the patriarchate to the supremacy of Rome. In October 1369 John, having travelled through Naples to Rome, formally converted to Catholicism in St Peter's Basilica and recognized the pope as supreme head of the Church. He was not accompanied by the clergy of the Byzantine Church and the move failed to bring about an end to the Schism.
Impoverished by war, he was detained as a debtor when he visited Venice in 1369 on his way back from Rome and was later captured on his way back through Bulgarian territories. In 1371, he recognized the suzerainty of the Ottoman sultan Murad I. Murad later assisted him against his son Andronikos when the latter deposed him in 1376.
Deposition and second rule.
In 1390, his grandson John VII briefly usurped the throne, but was quickly overthrown. The same year, John V ordered the strengthening of the Golden Gate in Constantinople, utilizing marble from the decayed churches in and around the city. Upon completion of this construction, Bayezid I demanded that John raze these new works, threatening war and the blinding of his son Manuel, whom he held in captivity. John V filled the Sultan's order but is said to have suffered from this humiliation and died soon thereafter on 16 February 1391.
John V was finally succeeded to the imperial throne by his son Manuel. His younger son Theodore had already acceded to the Despotate of Morea in 1383.
Family.
John V married Helena Kantakouzene, daughter of his co-emperor John VI Kantakouzenos and Irene Asanina, on 28 May 1347. They had at least six children -- four sons and at least two daughters. Their known children include: