Year 284 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Tucca and Denter/Dentatus (or, less frequently, year 470 Ab urbe condita). The denomination 284 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Lysimachus' wife, Arsinoe, being keen to gain the succession to the kingdom of Thrace for her sons in preference to Agathocles (the eldest son of Lysimachus), intrigues against him with the help of her brother Ptolemy Keraunos. They accuse him of conspiring with Seleucus to seize the throne, and Agathocles is put to death. This atrocious deed by Lysimachus and his family arouses great indignation. Many of the cities in Asia Minor revolt and some of his most trusted friends desert him.
Agathocles' widow Lysandra flees with their children and with Alexander, Agathocles' brother, to the court of Seleucus, who at once invades Lysimachus' territory in Asia Minor.