War between Syracuse and Carthage follows.Agathocles is…

The coalition has from 315 BCE to 311 BCE fought indecisively against Antigonus, who has shown himself energetic, resourceful, and imaginative, but unable to strike a decisive blow.

In view of this new threat from the East, Antigonus decides to make peace with all of his adversaries except Seleucus.

He orders Nicanor, one of his generals, to invade Babylonia from the east and his son Demetrius to attack it from the west, but they fail to oust Seleucus.

Agathocles invades the last Carthaginian holdings on Sicily in 311 BCE, thereby breaking the terms of the current peace treaty, and lays siege to Akragas.

Military success had seemed to flow with the Samnites until 314 BCE.

Campania is on the verge of deserting Rome.

Peace is established between Rome and some Samnite towns.

The tide of the war turns in 311, when the Samnites are joined by Etruscan cities that have decided to join a showdown against Roman power.

However, the Samnites are unable to prevent the Romans from establishing fortified colonies around the edges of the Samnite state; these serve as bases for attack.

Agathocles saves himself from certain disaster in 310 BCE by breaking through the blockade and attacking his enemy's homelands in Africa with considerable success.

…besieged in Syracuse.

All the other Diadochi (Alexander's successors) confirm the existing boundaries and the freedom of the Greek cities.

Antigonus, no longer regent but merely strategos (officer in charge) of the whole of Asia, is to rule in Syria and from the Hellespont to the Euphrates, leaving Lysimachus with Thrace, Cassander with Greece and Macedonia (but only until Alexander IV comes of age in 305), and …

…Ptolemy with Egypt and Cyprus.

Ptolemy suppresses the island's kingdoms and in 310 forces the last king of Salamis, Nicocreon, to commit suicide, together with all his family. (For the next two and a half centuries, Cyprus will remain a Ptolemaic possession, ruled by a strategos, or governor-general.)

Ptolemy next attacks Cilicia, sparking the second coalition war (310-301) against Antigonus.

Defenders of the Argead dynasty have begun to declare, following the treaty, that Alexander IV should now exercise full power and that a regent is no longer needed.

The response of the Macedonian regent Cassander, his ruthlessness toward Alexander's family partly dictated by political considerations, is definitive: to secure his rule, in 310 BCE or 309 BCE, he commands the Macedonian general Glaucias to secretly assassinate Alexander IV and his mother Roxana.

The orders are carried out, and they are both poisoned.

Hamilcar, grandson of Hanno the Navigator, successfully leads the Carthaginian counterattack.

He controls almost all of Sicily by 310 BCE, and has laid siege to Syracuse itself.