Seleucus managed to maintain himself in the interior of Asia Minor and made arrangements to shore up his power there.
One of his sisters married Mithridates II of Pontus, another married Ariarathes III of Cappadocia and he married his cousin Laodice II, by whom he had five children including Antiochis, Seleucus III Ceraunus and Antiochus III the Great.
Seleucus then appointed his brother Antiochus Hierax as viceroy in Asia Minor and marched against the Ptolemies.

Ptolemy III returned to Egypt in 245 BC, reputedly taking with him 40,000 talents of gold and the statues of Egyptian gods which had been looted centuries before by the Persians.
Seleucus crossed into Babylonia and Mesopotamia first, receiving the loyalty of the empire's Eastern regions and then marched into Syria where he recovered Antioch by 244 BC.
This was followed by the recapture of the other major cities in the area.
By 242 BC the interior of Northern Syria had been regained and Seleucus was even able to launch raids into Ptolemaic controlled Syria around Damascus.

Elsewhere the Seleucid's were less successful.
In the Aegean the Ptolemaic armies were able to seize control of Ephesos, as well as Ainos and Maroneia in Thrace, and several cities on the Asian side of the Hellespont.

In 241 BC peace was finally agreed and a treaty signed.
 Ptolemy recognised Seleucus as king and the Eleutheros river was once again accepted as the boundary between the two empires in Syria.
Ptolemy did however retain his conquests in Thrace, Ephesos and, most importantly of all, the vital port of Seleucia Pieria.
This city contained the tomb of the Seleucid dynasty's founder, Seleucus I, and controlled much of the trade from Antioch.
The Seleucid desire to recover the city would prove to be one of the main causes of the outbreak of the Fourth Syrian war in 219 BC.

In the meantime, Antiochus Hierax, had set himself up as a rival in Asia Minor against Seleucus, supported by their domineering mother Laodice.
Seleucus appears to have launched an attack against Antiochus Hierax, but was unable to take Sardis.
After two years of stalemate, the brothers met at the Battle of Ancyra around 237 BC.
With the support of Mithridates II of Pontus and the Galatians Antiochus Hierax was victorious and Seleucus was barely able to escape with his life.
After this Seleucus left the country beyond the Taurus to his brother and the other powers of Anatolia and an uneasy peace between the two prevailed.
Seleucus managed to maintain himself in the interior of Asia Minor and made arrangements to shore up his power there. One of his sisters married Mithridates II of Pontus, another married Ariarathes III of Cappadocia and he married his cousin Laodice II, by whom he had five children including Antiochis, Seleucus III Ceraunus and Antiochus III the Great. Seleucus then appointed his brother Antiochus Hierax as viceroy in Asia Minor and marched against the Ptolemies. 
Ptolemy III returned to Egypt in 245 BC, reputedly taking with him 40,000 talents of gold and the statues of Egyptian gods which had been looted centuries before by the Persians. Seleucus crossed into Babylonia and Mesopotamia first, receiving the loyalty of the empire's Eastern regions and then marched into Syria where he recovered Antioch by 244 BC. This was followed by the recapture of the other major cities in the area. By 242 BC the interior of Northern Syria had been regained and Seleucus was even able to launch raids into Ptolemaic controlled Syria around Damascus. 
Elsewhere the Seleucid's were less successful. In the Aegean the Ptolemaic armies were able to seize control of Ephesos, as well as Ainos and Maroneia in Thrace, and several cities on the Asian side of the Hellespont. 
In 241 BC peace was finally agreed and a treaty signed.  Ptolemy recognised Seleucus as king and the Eleutheros river was once again accepted as the boundary between the two empires in Syria. Ptolemy did however retain his conquests in Thrace, Ephesos and, most importantly of all, the vital port of Seleucia Pieria. This city contained the tomb of the Seleucid dynasty's founder, Seleucus I, and controlled much of the trade from Antioch. The Seleucid desire to recover the city would prove to be one of the main causes of the outbreak of the Fourth Syrian war in 219 BC.
In the meantime, Antiochus Hierax, had set himself up as a rival in Asia Minor against Seleucus, supported by their domineering mother Laodice. Seleucus appears to have launched an attack against Antiochus Hierax, but was unable to take Sardis. After two years of stalemate, the brothers met at the Battle of Ancyra around 237 BC. With the support of Mithridates II of Pontus and the Galatians Antiochus Hierax was victorious and Seleucus was barely able to escape with his life. After this Seleucus left the country beyond the Taurus to his brother and the other powers of Anatolia and an uneasy peace between the two prevailed.
Seleucus II Callinicus