Year 246 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Crassus and Licinus (or, less frequently, year 508 Ab urbe condita). The denomination 246 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.
Antiochus II leaves Berenice in order to live again with his former wife Laodice and his son Seleucus. However, Laodice poisons him and proclaims her son as King Seleucus II Callinicus, while her supporters in Antioch kill Berenice and her children who have taken refuge at Daphne, near Antioch, in Syria.
Berenice's brother, Ptolemy III, sets about to avenge his sister's murder by invading Syria which begins the Third Syrian War (also known as the Laodicean War). Ptolemy III's navy, perhaps with the aid of rebels in the cities, advances against Seleucus II's forces as far as Thrace, across the Hellespont, and also captures some islands off the Anatolian coast.
Seleucus II Callinicus' mother, Laodice attempts to take control over the Seleucid Empire by insisting that Seleucus II make his younger brother, Antiochus Hierax, co-regent and give him all the Seleucid territory in Anatolia. Antiochus promptly declares independence and begins fighting a war with his brother.
In order to secure the Bactrian King Diodotus' friendship, Seleucus II Callinicus arranges the marriage of one of his sisters to King Diodotus.
With Hamilcar Barca wearing the Romans down in Sicily, the Romans, by private subscription, build another fleet with the aim of regaining command of the sea.
In Rome, the number of praetors is increased from one to two. The second praetor is appointed to relieve the backlog of judicial business and to give the Republic a magistrate with Imperium who can field an army in an emergency when both consuls are away fighting a war.
An irrigation canal approximately one hundred miles long is built across the current-day province of Shaanxi in China, greatly adding to the agricultural productivity of the area and to the military potency of the Qin dynasty.
Ptolemy II Philadelphus, king of Egypt from 285 BC, second king of the Ptolemaic dynasty, who has extended his power by skilful diplomacy, developed agriculture and commerce, and made Alexandria a leading centre of the arts and sciences (b. 308 BC)