"Tiberius Claudius Caesar Britannicus (c. 12 February AD 41 – 11 February AD 55), usually called Britannicus, was the son of Roman emperor Claudius and his ...
third wife Valeria Messalina. For a time he was considered his father´s heir, but that changed after his mother´s downfall in 48, when it was revealed she had engaged in a bigamous marriage without Claudius´ knowledge. The next year, his father married Agrippina the Younger, Claudius´ fourth and final marriage. Their marriage was followed by the adoption of Agrippina´s son, Lucius Domitius, whose name became Nero as a result. His step-brother would later be married to his sister Octavia, and soon eclipsed him as Claudius´ heir. Following his father´s death in October 54, Nero became emperor. The sudden death of Britannicus shortly before his fourteenth birthday is reported by all extant sources as a poisoning on Nero´s orders—as Claudius´ natural son, he represented a threat to Nero´s claim to the throne." - (en.wikipedia.org 30.10.2019)
