John V Palaiologos or Palaeologus (, Iōánnēs Palaiológos; 18 June 1332 – 16 February 1391) was Byzantine emperor from 1341 to 1391, with interruptions. 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