First Syrian War
The First Syrian War (274–271 BCE) occurred ten years into the rule of Ptolemy II Philadelphus over the Ptolemaic Kingdom in Egypt. At the time the king of the Seleucid Empire named Antiochus I Soter attempted to expand his empire into Anatolia as well as northern Coele-Syria. However, Ptolemy was not about to cede any of the territory that his father had worked so hard to preserve so he launched a military campaign to halt Antiochus I.
One of the variables that allowed Ptolemy II to carry out a successful military campaign during this period was that his recent marriage to his sister Arsinoe II was able to ease the social strife that was occurring in the Egyptian court at the time. Arisnoe II was very adept at understanding the day to day workings of the court and this allowed Ptolemy II to campaign.
The First Syrian War would be a victory for the Ptolemaic Dynasty of Egypt who managed to capture the coastal regions of Coele-Syria as well as southern Anatolia in a single rapid advance. Following this Ptolemy II would launch subsequent military campaigns and by 271 BCE he extended the borders of the Ptolemaic Kingdom as far north as Caria and Cilicia.
From here Ptolemy II Philadelphus would focus on acquiring territory more further eastward and would consider the neighboring kingdom of Cyrenaica. His half-brother Magas was the ruler of Cyrene at the time and wanted to remain independent of the Ptolemies. Eventually in 250 BCE the kingdom of Cyrenaica was absorbed into the domain of the Ptolemaic Kingdom.