(3rd century BC), five conflicts fought between the leading Hellenistic states, chiefly the Seleucid kingdom and Ptolemaic Egypt, and, in a lesser way, Macedonia. The complex and devious diplomacy that surrounded the wars was characteristic of the Hellenistic monarchies. The main issue in dispute between the Seleucids (Seleucid kingdom) and the Ptolemies was control of southern Syria. In the First War (274–271) Ptolemy II (Ptolemy II Philadelphus) wrested Phoenicia on the northern Syrian coast, most of Anatolia, and the Cyclades Islands from the Seleucids. In the Second War (c. 260–255/253) the Seleucid king Antiochus II (Antiochus II Theos), aided by Antigonus Gonatus of Macedonia, initiated a largely successful campaign to regain Phoenicia and Anatolia.

The Third, or Laodicean, War (c. 245–241) was begun by Ptolemy III (Ptolemy III Euergetes) to enforce earlier diplomatic arrangements disadvantageous to Seleucus II (Seleucus II Callinicus), son and successor of Antiochus II. To consolidate his position, Seleucus had to concede territory in Anatolia to the rulers of Cappadocia and Pontus. By the peace terms Ptolemy kept Seleucia Pieria in Syria and several coastal areas in Thrace.

In 236 Seleucus was forced to cede his Anatolian possessions to his brother Antiochus Hierax in the so-called War of the Brothers. Antiochus in turn lost them to the Anatolian ruler Attalus I of Pergamum. The former eastern Seleucid provinces, Bactria and Parthia, were also by this time in the hands of independent rulers. By 221 Antiochus III began to implement a policy of restoring Seleucid power, largely successful except for an abortive attack on Egypt.

In the Fourth War (219–217), which he initiated, Antiochus (Antiochus III) had to concede Coele Syria (southern Syria and Palestine) to Ptolemy IV, whose victory at Raphia in Palestine, however, was clouded by revolts in Egypt.

The Fifth War (202–200) climaxed a renewed and permanently successful Seleucid effort to wrest Coele Syria from the Ptolemies. Antiochus' subsequent Hellenizing policy in Judaea led to rebellion and independence for Judaea in 142. Weakened by constant warfare, the Hellenistic states fell under Roman control in the 2nd and 1st centuries BC.