Agrippina the Younger outraged by Claudius' adoption of Nero and his choice of Nero as successor, instead of choosing his own son Britannicus. Nero and Octavia were married on June 9, 53. Claudius later repented of marrying Agrippina and adopting Nero, began to favor Britannicus, and started preparing him for the throne. His actions allegedly gave Agrippina a motive to eliminate Claudius. The ancient sources say she poisoned Claudius on October 13, 54 with a plate of deadly mushrooms at a banquet, thus enabling Nero to quickly take the throne as emperor. Accounts vary wildly with regard to this private incident and according
Agrippina the Elder to Augustus, a significant factor in the marriages of the emperors and princes of the dynasty. The Annals repeatedly has Agrippina competing for influence with Tacitus simply because she is related to Augustus biologically. Tacitus presents Agrippina as being kindred to aristocratic males, and has her reversing gender roles, which showcases her assumption of male "auctoritas" ("authority") with metaphors of her dressing and undressing. In an example of Agrippina assuming "auctoritas", he says: Using the above epithet, ""(femina) ingens animi"" ("..[a woman], great for her courage"), he assigns a haughty attitude to Agrippina that compels her to explore the affairs