The Syrian Wars were a series of six wars between the Seleucid Empire and the Ptolemaic Kingdom of Egypt, successor states to Alexander the Great's empire, during the 3rd and 2nd centuries BC over the region then called Coele-Syria, one of the few avenues into Egypt. These conflicts drained the material and manpower of both parties and led to their eventual destruction and conquest by Rome and Parthia. They are briefly mentioned in the biblical Books of the Maccabees.
In the Wars of the Diadochi following Alexander's death, Coele-Syria initially came under the rule of Antigonus I Monophthalmus. In 301 BC Ptolemy I Soter, who four years earlier had crowned himself King of Egypt, exploited events surrounding the Battle of Ipsus to take control of the region. The victors at Ipsus, however, had allocated Coele-Syria to Ptolemy's former ally Seleucus I Nicator, founder of the Seleucid Empire. Seleucus, who had been aided by Ptolemy during his ascent to power, did not take any military action to reclaim the region. Once both were dead, however, their successors became embroiled in war.
A decade into his rule, Ptolemy II faced Antiochus I, the Seleucid king who was trying to expand his empire's holdings in Syria and Anatolia. Ptolemy proved to be a forceful ruler and skilled general. In addition, his recent marriage to his court-wise sister Arsinoe II of Egypt had stabilized the volatile Egyptian court, allowing Ptolemy to successfully carry out the campaign.
The First Syrian War was a major victory for the Ptolemies. Antiochus took the Ptolemaic controlled areas in coastal Syria and southern Anatolia in his initial rush. Ptolemy reconquered these territories by 271 BC, extending Ptolemaic rule as far as Caria and into most of Cilicia. With Ptolemy's eye focused eastward, his half-brother Magas declared his province of Cyrenaica to be independent. It would remain independent until 250 BC, when it was reabsorbed into the Ptolemaic Kingdom.